diff --git a/app/javascript/packages/i18n/CHANGELOG.md b/app/javascript/packages/i18n/CHANGELOG.md
index fddaf37c74b..1a8789b667a 100644
--- a/app/javascript/packages/i18n/CHANGELOG.md
+++ b/app/javascript/packages/i18n/CHANGELOG.md
@@ -1,4 +1,6 @@
-# `Change Log`
+## Unreleased
+
+- Output console error message when translation data missing for requested key.
 
 ## 1.0.1
 
diff --git a/app/javascript/packages/i18n/index.spec.ts b/app/javascript/packages/i18n/index.spec.ts
index 96a07b0e933..2afc5b5b7c7 100644
--- a/app/javascript/packages/i18n/index.spec.ts
+++ b/app/javascript/packages/i18n/index.spec.ts
@@ -1,3 +1,4 @@
+import { useDefineProperty } from '@18f/identity-test-helpers';
 import { I18n, replaceVariables } from './index';
 
 describe('replaceVariables', () => {
@@ -37,6 +38,23 @@ describe('I18n', () => {
       expect(t('unknown')).to.equal('unknown');
     });
 
+    context('in non-test environment', () => {
+      const defineProperty = useDefineProperty();
+      beforeEach(() => {
+        defineProperty(process.env, 'NODE_ENV', {
+          value: 'production',
+          configurable: true,
+          writable: true,
+          enumerable: true,
+        });
+      });
+
+      it('falls back to key value and logs to console', () => {
+        expect(t('unknown')).to.equal('unknown');
+        expect(console).to.have.loggedError('Missing translation for key `unknown`.');
+      });
+    });
+
     describe('pluralization', () => {
       it('throws when count is not given', () => {
         expect(() => t('messages')).to.throw(TypeError);
diff --git a/app/javascript/packages/i18n/index.ts b/app/javascript/packages/i18n/index.ts
index 9183bdbd5a8..cd5c438226c 100644
--- a/app/javascript/packages/i18n/index.ts
+++ b/app/javascript/packages/i18n/index.ts
@@ -29,8 +29,21 @@ const getPluralizationKey = (count: number): keyof PluralizedEntry =>
  *
  * @return Entry string or object.
  */
-const getEntry = (strings: Entries, key: string): Entry =>
-  Object.hasOwn(strings, key) ? strings[key] : key;
+function getEntry(strings: Entries, key: string): Entry {
+  if (Object.hasOwn(strings, key)) {
+    return strings[key];
+  }
+
+  if (process.env.NODE_ENV !== 'test') {
+    // String data is not populated in JavaScript tests, so falling back to the key is the expected
+    // behavior. In all other environments this is an unexpected behavior, so log accordingly.
+
+    // eslint-disable-next-line no-console
+    console.error(`Missing translation for key \`${key}\`.`);
+  }
+
+  return key;
+}
 
 /**
  * Returns true if the given entry is a pluralization entry, or false otherwise.
diff --git a/scripts/enforce-typescript-files.mjs b/scripts/enforce-typescript-files.mjs
index df91c749c32..62860455c9a 100755
--- a/scripts/enforce-typescript-files.mjs
+++ b/scripts/enforce-typescript-files.mjs
@@ -26,7 +26,6 @@ const LEGACY_FILE_EXCEPTIONS = [
   'spec/javascript/packs/form-steps-wait-spec.js',
   'spec/javascript/packs/state-guidance-spec.js',
   'spec/javascript/packs/webauthn-setup-spec.js',
-  'spec/javascript/support/console.js',
   'spec/javascript/support/document-capture.jsx',
   'spec/javascript/support/dom.js',
   'spec/javascript/support/file.js',
diff --git a/spec/javascript/support/console.js b/spec/javascript/support/console.ts
similarity index 56%
rename from spec/javascript/support/console.js
rename to spec/javascript/support/console.ts
index 539e7107b94..6f26cdc74aa 100644
--- a/spec/javascript/support/console.js
+++ b/spec/javascript/support/console.ts
@@ -1,7 +1,18 @@
 /* eslint-disable no-console */
 
+import { format } from 'node:util';
 import sinon from 'sinon';
-import { format } from 'util';
+import type Chai from 'chai';
+
+declare global {
+  namespace Chai {
+    interface Assertion {
+      loggedError: (message: string | RegExp) => Chai.Assertion;
+    }
+  }
+}
+
+let unverifiedCalls: string[] = [];
 
 /**
  * Chai plugin which adds chainable `logged` method, to be used in combination with
@@ -10,33 +21,33 @@ import { format } from 'util';
  * @see https://www.chaijs.com/guide/plugins/
  * @see https://www.chaijs.com/api/plugins/
  *
- * @param {import('chai')}                chai  Chai object.
- * @param {import('chai/lib/chai/utils')} utils Chai plugin utilities.
+ * @param chai Chai object.
+ * @param utils Chai plugin utilities.
  */
-export function chaiConsoleSpy(chai, utils) {
+export const chaiConsoleSpy: Chai.ChaiPlugin = (chai, utils) => {
   utils.addChainableMethod(
     chai.Assertion.prototype,
     'loggedError',
-    (message) => {
+    (message: string | RegExp) => {
       if (message) {
-        const index = console.unverifiedCalls.findIndex((calledMessage) =>
+        const index = unverifiedCalls.findIndex((calledMessage) =>
           message instanceof RegExp ? message.test(calledMessage) : message === calledMessage,
         );
         let error = `Expected console to have logged: ${message}. `;
-        error += console.unverifiedCalls
-          ? `Console logged with: ${console.unverifiedCalls.join(', ')}`
+        error += unverifiedCalls
+          ? `Console logged with: ${unverifiedCalls.join(', ')}`
           : 'Console did not log.';
 
         expect(index).to.not.equal(-1, error);
 
-        console.unverifiedCalls.splice(index, 1);
+        unverifiedCalls.splice(index, 1);
       } else {
-        console.unverifiedCalls = [];
+        unverifiedCalls = [];
       }
     },
     undefined,
   );
-}
+};
 
 /**
  * Test lifecycle helper which stubs `console.error` and verifies that any logging which occurs to
@@ -44,19 +55,25 @@ export function chaiConsoleSpy(chai, utils) {
  * `chaiConsoleSpy` Chai plugin.
  */
 export function useConsoleLogSpy() {
-  let originalConsoleError;
-  beforeEach(() => {
-    console.unverifiedCalls = [];
+  let originalConsoleError: Console['error'];
+  before(() => {
     originalConsoleError = console.error;
     console.error = sinon.stub().callsFake((message, ...args) => {
-      console.unverifiedCalls = console.unverifiedCalls.concat(format(message, ...args));
+      unverifiedCalls.push(format(message, ...args));
     });
   });
 
+  beforeEach(() => {
+    unverifiedCalls = [];
+  });
+
   afterEach(() => {
-    console.error = originalConsoleError;
-    expect(console.unverifiedCalls).to.be.empty(
-      `Unexpected console logging: ${console.unverifiedCalls.join(', ')}`,
+    expect(unverifiedCalls).to.be.empty(
+      `Unexpected console logging: ${unverifiedCalls.join(', ')}`,
     );
   });
+
+  after(() => {
+    console.error = originalConsoleError;
+  });
 }
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index 6c27735fd6d..e766747e17c 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -77,7 +77,7 @@ class Analytics
       # rubocop:enable Style/GlobalVars
       # rubocop:disable Rails/Output
       print '                       Bundling JavaScript and stylesheets... '
-      system 'yarn concurrently "yarn:build:*" > /dev/null 2>&1'
+      system 'NODE_ENV=production yarn concurrently "yarn:build:*" > /dev/null 2>&1'
       puts '✨ Done!'
       # rubocop:enable Rails/Output
 
diff --git a/webpack.config.js b/webpack.config.js
index eb46a9bd0b1..1c12ee0f964 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -11,7 +11,6 @@ const env = process.env.NODE_ENV || process.env.RAILS_ENV || 'development';
 const host = process.env.HOST || 'localhost';
 const isLocalhost = host === 'localhost';
 const isProductionEnv = env === 'production';
-const isTestEnv = env === 'test';
 const mode = isProductionEnv ? 'production' : 'development';
 const hashSuffix = isProductionEnv ? '-[chunkhash:8].digested' : '';
 const devServerPort = process.env.WEBPACK_PORT;
@@ -88,9 +87,7 @@ module.exports = /** @type {import('webpack').Configuration} */ ({
     }),
     new RailsI18nWebpackPlugin({
       onMissingString(key, locale) {
-        if (isTestEnv) {
-          throw new Error(`Unexpected missing string for locale '${locale}': '${key}'`);
-        }
+        throw new Error(`Unexpected missing string for locale '${locale}': '${key}'`);
       },
     }),
     new RailsAssetsWebpackPlugin(),