[wallet/symbol/mobile] fix: localization mess

[OlegMakarenko]

Problem

English (en.json) is the only locale file that feeds the UI with up-to-date text, and it degraded over time:

• Many unused localization keys that were never cleaned up. Some of them even from the Opt-in era.
• No naming rules at all - key structure and format were inconsistent, several conventions mixed together.
• Some texts duplicated under different keys.
• Raw error code strings and raw numeric transaction type descriptors were passed straight to the translation layer.
• The other language files were not updated for a long time - keys and translations are outdated.

Solution

1. Localization guidelines

Researched, finalized and committed as wallet/symbol/mobile/docs/localization.md. The core rules:

• Keys are flat: segments joined with _, camelCase inside a segment.
• After the scope prefix, a key is a chain of element–name pairs:
  <element>_<name>[_<element>[_<name>]], at most 7 segments in total.

Scope	Pattern	Example
Global	<element>_<name>…	button_ok
Screen	screen_<folder>[_<section>]_…	screen_bridge_swap_dialog_confirm_title
Component	component_<componentName>_…	component_navigationMenu_tab_home

• Element words come from a fixed vocabulary (button, dialog, title, fieldTitle, errorMessage, …); names are free camelCase words chosen by meaning.
• Always pick the widest scope that fits; never duplicate a text under a narrower key.
• Keys are literal strings - no building keys from variables, except a few registered runtime builders and mapper tables.
• Placeholders use one format: %{name}.

2. en.json cleanup

• Analyzed key usage across the app; removed unused keys.
• Removed duplications.
• Renamed all keys to follow the new pattern and rules; sorted the file alphabetically.
• Proofread the English texts: fixed grammar, typos, and unified template placeholders.

3. Mapper functions (src/utils/localization.js)

• Errors: every error now has its own key in the locale file, and getErrorMessageLocaleKey(code) maps error codes to those keys — no more raw code strings passed to the translation function. Unknown codes fall back to a generic message.
• Transaction types: getTransactionTypeLocaleKey(type, chainName, direction) maps the raw chain-specific numeric descriptors to human-readable locale keys (and getReceiptTypeLocaleKey does the same for receipt types).

4. Test system enforcing the guidelines (3 files)

File	What it enforces
__tests__/localization/en-json.test.js	File format (sorted keys, no duplicates, canonical formatting). Every key follows the pattern structure, element words come from the whitelist, and scopes are real: the test reads the actual src/screens and src/components directories and rejects keys pointing to a screen or component that does not exist.
__tests__/localization/translations.test.js	Each registered translation file has exactly the same keys as en.json, no extra keys, and the same key order. A registry check ensures every file in the locales directory is consciously listed.
__tests__/utils/localization.test.js	Input/output tests for the error, transaction type and receipt type mappers, plus a completeness check that every mapper output is an existing en.json key.

5. Usage updates

• All UI code and the existing tests were updated to use the renamed keys.

The other locale files (cn/ja/ko/uk/zh) are kept temporarily to reuse texts from; they will be rewritten from scratch separately and added to the consistency test one by one as they land.

[codecov]

Codecov Report

❌ Patch coverage is 96.93685% with 65 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.19%. Comparing base (c50933c) to head (b8088a7).
⚠️ Report is 2 commits behind head on dev.

Files with missing lines	Patch %	Lines
...rc/screens/bridge/components/EstimationSummary.jsx	73.68%	15 Missing ⚠️
...reens/bridge/hooks/useBridgeTransactionWorkflow.js	87.35%	11 Missing ⚠️
...ile/src/screens/bridge/components/SwapSelector.jsx	87.03%	7 Missing ⚠️
wallet/symbol/mobile/src/localization/index.js	60.00%	6 Missing ⚠️
.../src/app/components/NetworkConnectionStatusBar.jsx	20.00%	4 Missing ⚠️
...le/src/screens/mosaic/components/InputDuration.jsx	66.66%	4 Missing ⚠️
...et/symbol/mobile/src/screens/bridge/BridgeSwap.jsx	97.67%	2 Missing ⚠️
...le/src/screens/multisig/widgets/MultisigWidget.jsx	0.00%	2 Missing ⚠️
...bol/mobile/src/components/controls/InputAmount.jsx	66.66%	1 Missing ⚠️
...rc/components/display/Token/ExpirationProgress.jsx	50.00%	0 Missing and 1 partial ⚠️
... and 12 more

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #2571      +/-   ##
==========================================
+ Coverage   95.83%   96.19%   +0.35%     
==========================================
  Files         786      744      -42     
  Lines       60742    56625    -4117     
  Branches     1696     1665      -31     
==========================================
- Hits        58214    54469    -3745     
+ Misses       2460     2089     -371     
+ Partials       68       67       -1     

Flag	Coverage Δ
explorer-puller	?
explorer-rest	?
wallet-common-ethereum	99.11% <ø> (ø)
wallet-mobile-symbol	95.53% <96.93%> (+1.15%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ymbol/mobile/src/app/components/NavigationMenu.jsx	84.61% <100.00%> (-1.93%)	⬇️
...bol/mobile/src/components/controls/FeeSelector.jsx	94.89% <100.00%> (ø)
...bol/mobile/src/components/controls/SelectToken.jsx	100.00% <100.00%> (ø)
...rc/components/controls/SelectTransactionSender.jsx	92.89% <100.00%> (ø)
...mbol/mobile/src/components/display/MessageView.jsx	100.00% <100.00%> (ø)
...e/src/components/display/Token/TokenBalanceRow.jsx	100.00% <100.00%> (ø)
...ile/src/components/display/Token/TokenListItem.jsx	100.00% <100.00%> (ø)
...ents/features/Passcode/hooks/usePasscodeManager.js	96.02% <100.00%> (+0.56%)	⬆️
...le/src/components/features/Passcode/utils/index.js	84.48% <100.00%> (ø)
...ile/src/components/features/SendReceiveButtons.jsx	98.92% <100.00%> (ø)
... and 118 more

... and 47 files with indirect coverage changes

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