Sonic and Eleven v4 share 44 language codes on Sume

On Sume the catalog lists 44 language codes for Sonic 3.x and the same 44 for Eleven v3 and v4, so the language field does not decide which engine to use. In tts-router-models.ts the Eleven v3 and v4 list is defined as the union of the Turbo v2.5 list (31 codes) and the Sonic 3 list (44 codes), which is exactly the Sonic list. A source comment says the real Eleven v3 and v4 families cover 70+ languages, and only the codes both families share are listed.

Counted from the repo on origin/main b28f3b0, read 2026-10-13.

So how do I pick?

Pick on what else you need: Sonic if you want timestamps, segmentation, avatar voices or WAV; Eleven if you need its voices or seed (v4 rows). Set language to the primary language of the script. A known mismatch with the voice's own language returns HTTP 409 tts_voice_language_mismatch; retry the same request and idempotency key with confirm_language_mismatch: true once you have checked it.

What about languages outside the list?

The catalog is the guard: the request is validated against it. If your language is not listed for the model you chose, pick a row that lists it, or generate the voice outside Sume and import the audio.