Build compatible themes and plugins

Do

• Keep one canonical WordPress object and request its localized value.
• Register stable public strings and supported content fields.
• Carry an explicit locale into cron, queues, REST, AJAX, and email work.
• Preserve HTML, printf, shortcode, and merge-tag placeholders.
• Use localized URL helpers instead of manually adding prefixes.
• Include locale in fragment and object cache keys.
• Escape translated output for its final context.
• Test missing translations and source fallbacks.

Do not

• Create one duplicate post per language to satisfy an integration.
• Read or write POM Translate custom tables directly.
• Trigger remote translation from a visitor request.
• translate IDs, tokens, classes, prices, or whole unknown JSON structures.
• derive background locale from cookies or administrator preferences.
• concatenate a language prefix onto an already localized URL.
• cache multilingual output under a shared key.
• expose license data, customer content, or translation payloads in logs.

Review

Deactivate POM Translate and confirm the integration still produces usable base-language output. Reactivate it and verify two languages in the same process or cache lifetime. The most common compatibility failures are leaked locale state, over-broad string extraction, damaged placeholders, and locale-neutral caches.