diff --git a/web-ui/app/_lib/agents.ts b/web-ui/app/_lib/agents.ts
index 5309f2dba..efb6c116b 100644
--- a/web-ui/app/_lib/agents.ts
+++ b/web-ui/app/_lib/agents.ts
@@ -1,4 +1,5 @@
 import { ApiError } from './api';
+import type { LocalizedMarkdown } from './storeTypes';
 
 /**
  * Typed client for the operator multi-orchestrator REST surface
@@ -821,9 +822,16 @@ export type SetupFieldType =
 
 export interface PluginSetupFieldDto {
   key: string;
-  label: string;
+  /** #602 (OM-17) — the manifest loader normalises `label` into a
+   *  `{ <locale>: text }` map (`?? { en: key }`), so this is NOT a plain
+   *  string on any current middleware. Rendering it directly threw React #31
+   *  ("Objects are not valid as a React child") and took the whole orchestrator
+   *  page down via the route error boundary. Resolve with `pickLocalized`.
+   *  The bare-string arm covers payloads from a pre-#602 middleware. */
+  label: LocalizedMarkdown | string;
   type: SetupFieldType;
-  help?: string;
+  /** #602 (OM-17) — localized help map; same contract as `label`. */
+  help?: LocalizedMarkdown | string;
   default?: string | string[];
   enum?: Array<{ value: string; label: string }>;
 }
diff --git a/web-ui/app/_lib/localized.ts b/web-ui/app/_lib/localized.ts
index a6e907993..68230ee69 100644
--- a/web-ui/app/_lib/localized.ts
+++ b/web-ui/app/_lib/localized.ts
@@ -5,11 +5,18 @@ import type { LocalizedMarkdown } from './storeTypes';
  * locale. Falls back to English, then German, then any remaining locale, so a
  * guide that ships only one language still renders. Returns undefined when the
  * map is empty or absent.
+ *
+ * A bare string is returned as-is. The manifest loader normalises setup text
+ * into a map, but a payload from a pre-#602 middleware still ships the plain
+ * string — without this branch `Object.values('abc')` would resolve to `'a'`.
  */
 export function pickLocalized(
-  map: LocalizedMarkdown | undefined,
+  map: LocalizedMarkdown | string | undefined,
   locale: string,
 ): string | undefined {
+  if (typeof map === 'string') {
+    return map.trim().length > 0 ? map : undefined;
+  }
   if (!map) return undefined;
   const direct = map[locale];
   if (direct && direct.trim().length > 0) return direct;
diff --git a/web-ui/app/operator/agents/_components/PluginsDnd.tsx b/web-ui/app/operator/agents/_components/PluginsDnd.tsx
index d8050137f..48c27acfd 100644
--- a/web-ui/app/operator/agents/_components/PluginsDnd.tsx
+++ b/web-ui/app/operator/agents/_components/PluginsDnd.tsx
@@ -21,9 +21,10 @@ import {
 import { CSS } from '@dnd-kit/utilities';
 import { GripVertical } from 'lucide-react';
 import { useMemo, useState } from 'react';
-import { useTranslations } from 'next-intl';
+import { useLocale, useTranslations } from 'next-intl';
 
 import { Button } from '@/app/_components/ui/Button';
+import { pickLocalized } from '@/app/_lib/localized';
 import type {
   OperatorAgentDto,
   PluginCatalogEntryDto,
@@ -780,6 +781,14 @@ function PluginConfigField(props: {
   onChange: (value: string | boolean | number | string[]) => void;
 }): React.ReactElement {
   const { field, value, disabled, onChange } = props;
+  const locale = useLocale();
+  // #602 (OM-17) — `label` / `help` arrive as `{ <locale>: text }` maps from
+  // the manifest loader. Rendering the map object straight into JSX threw
+  // React #31 and replaced the whole orchestrator page with the route error
+  // boundary the moment "Config" was clicked. `key` is the loader's own
+  // fallback for a label-less field, so it is the right last resort here too.
+  const label = pickLocalized(field.label, locale) ?? field.key;
+  const help = pickLocalized(field.help, locale);
   const isSecret = field.type === 'secret' || field.type === 'password';
   const isHostList = field.type === 'host_list';
   const isEnum = field.type === 'enum' && (field.enum?.length ?? 0) > 0;
@@ -789,9 +798,9 @@ function PluginConfigField(props: {
   return (
     <label className="flex flex-col gap-0.5">
       <span className="text-[10px] uppercase tracking-wide text-[color:var(--fg-muted)]">
-        {field.label}
-        {field.help && (
-          <span className="ml-1 text-[color:var(--fg-subtle)]">— {field.help}</span>
+        {label}
+        {help && (
+          <span className="ml-1 text-[color:var(--fg-subtle)]">— {help}</span>
         )}
       </span>
       {isSecret ? (
diff --git a/web-ui/app/operator/agents/_components/__tests__/PluginsDnd.localizedFields.test.tsx b/web-ui/app/operator/agents/_components/__tests__/PluginsDnd.localizedFields.test.tsx
new file mode 100644
index 000000000..68c3960fb
--- /dev/null
+++ b/web-ui/app/operator/agents/_components/__tests__/PluginsDnd.localizedFields.test.tsx
@@ -0,0 +1,134 @@
+import { screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { describe, expect, it, vi } from 'vitest';
+
+import type {
+  OperatorAgentDto,
+  PluginCatalogEntryDto,
+} from '../../../../_lib/agents';
+import { renderWithIntl } from '../../../../_lib/test-utils';
+import { PluginsDnd } from '../PluginsDnd';
+
+/**
+ * Regression — clicking "Config" on an attached plugin blanked the whole
+ * orchestrator page with the route error boundary ("Etwas ist schiefgelaufen").
+ *
+ * Root cause: since #602 (OM-17) the manifest loader normalises every setup
+ * field's `label` / `help` into a `{ <locale>: text }` map (`?? { en: key }`),
+ * so NO field on a current middleware ships a bare string — 192 of 192 fields
+ * in the live catalog were maps. This component still rendered `field.label`
+ * straight into JSX, which is React #31 ("Objects are not valid as a React
+ * child"). It threw on the first render after the drawer opened, i.e. every
+ * plugin with setup fields was unconfigurable from this page.
+ *
+ * Guarded here: the drawer opens, the map resolves to the active locale, and
+ * a pre-#602 bare string still renders as itself.
+ *
+ * dnd-kit DRAG stays out of jsdom scope (see vitest.config.ts) — this drives
+ * the button, not the pointer sensor.
+ */
+
+function agent(): OperatorAgentDto {
+  return {
+    id: 'a1',
+    slug: 'marketing',
+    name: 'marketing',
+    privacyProfile: 'default',
+    enabled: true,
+    plugins: [{ id: '@omadia/confluence', config: {}, enabled: true }],
+    bindings: [],
+  } as unknown as OperatorAgentDto;
+}
+
+function catalog(
+  fields: PluginCatalogEntryDto['setup_fields'],
+): PluginCatalogEntryDto[] {
+  return [
+    {
+      id: '@omadia/confluence',
+      name: 'Confluence Connector',
+      kind: 'integration',
+      version: '0.3.3',
+      multi_instance: true,
+      privacy_class: 'default',
+      memory_reads: [],
+      memory_writes: [],
+      network_outbound: [],
+      setup_fields: fields,
+      depends_on: [],
+    },
+  ];
+}
+
+function renderDnd(
+  fields: PluginCatalogEntryDto['setup_fields'],
+  locale: 'de' | 'en' = 'en',
+): void {
+  renderWithIntl(
+    <PluginsDnd
+      agent={agent()}
+      catalog={catalog(fields)}
+      isFallback={false}
+      disabled={false}
+      onReplace={vi.fn()}
+    />,
+    { locale },
+  );
+}
+
+describe('PluginsDnd config drawer — localized setup fields', () => {
+  it('opens the drawer and renders a localized label map instead of crashing', async () => {
+    const user = userEvent.setup();
+    renderDnd([
+      {
+        key: 'confluence_base_url',
+        label: { en: 'Confluence Base URL', de: 'Confluence Basis-URL' },
+        type: 'string',
+        help: { en: 'No trailing slash needed.' },
+      },
+    ]);
+
+    await user.click(screen.getByRole('button', { name: 'Config' }));
+
+    expect(screen.getByText(/Confluence Base URL/)).toBeInTheDocument();
+    expect(screen.getByText(/No trailing slash needed\./)).toBeInTheDocument();
+  });
+
+  it('prefers the active locale', async () => {
+    const user = userEvent.setup();
+    renderDnd(
+      [
+        {
+          key: 'confluence_base_url',
+          label: { en: 'Confluence Base URL', de: 'Confluence Basis-URL' },
+          type: 'string',
+        },
+      ],
+      'de',
+    );
+
+    await user.click(screen.getByRole('button', { name: 'Config' }));
+
+    expect(screen.getByText(/Confluence Basis-URL/)).toBeInTheDocument();
+  });
+
+  it('still renders a bare string from a pre-#602 middleware', async () => {
+    const user = userEvent.setup();
+    renderDnd([
+      { key: 'legacy_key', label: 'Legacy Label', type: 'string' },
+    ]);
+
+    await user.click(screen.getByRole('button', { name: 'Config' }));
+
+    expect(screen.getByText(/Legacy Label/)).toBeInTheDocument();
+  });
+
+  it('falls back to the field key when the map is empty', async () => {
+    const user = userEvent.setup();
+    renderDnd([{ key: 'orphan_key', label: {}, type: 'string' }]);
+
+    await user.click(screen.getByRole('button', { name: 'Config' }));
+
+    expect(screen.getByText(/orphan_key/)).toBeInTheDocument();
+  });
+});