I use Lingui to translate my Application, and they support by default the .po syntax, but with ICU MessageFormat
They detail in the first link above the benefits of ICU vs Gettext plural.
Transifex does not seem to support ICU (only for JSON?). Would it be possible to add support for it?
Currently, Transifex fully supports ICU MessageFormat in JSON-based translation files, but its support for ICU within PO files is limited to traditional gettext-style pluralization (using msgid_plural and msgstr[n]).
If you continue using PO files, Transifex will handle pluralization via the standard Plural-Forms header and msgstr[n] entries (as shown in your examples). However, advanced ICU features (like nested selectors, exact number matching, etc.) won’t be fully supported.
If you switch to JSON format, you can leverage full ICU MessageFormat support in Transifex, which aligns better with Lingui’s capabilities.
Recommended Solutions:
Option 1 (Preferred): Use JSON message catalogs instead of PO files. Lingui supports this format, and Transifex handles ICU natively in JSON.
Option 2: Stick with PO files but use gettext-style plural rules (converting ICU plurals manually if needed).
Best regards,
Thank you Sandy for your reply!
I will analyze workarounds, eventually changing to JSON+ICU or just classic Gettext, but I just wanted to share the need for Gettext+ICU, in case that’s not on your roadmap 
cheers!