Clarify that hosted tts-v4 language support is broader than OSS ChatterboxMultilingualTTS

[Kaiyrly]

Description

There seems to be a documentation / product-positioning mismatch between the hosted Resemble product and the
open-source Chatterbox Multilingual model.

On the Resemble website / hosted product UI, Kazakh - Kazakhstan (kk-kz) is available as a selectable
language.

However, in the open-source ChatterboxMultilingualTTS model, the following call fails:

from chatterbox.mtl_tts import ChatterboxMultilingualTTS

model = ChatterboxMultilingualTTS.from_pretrained(device="cuda")
wav = model.generate(
    text="Сәлем, бүгін біз ашық нұсқадағы Chatterbox Multilingual моделін қазақ мәтінімен тексеріп
жатырмыз.",
    language_id="kk-kz",
)

It raises:

ValueError: Unsupported language_id 'kk-kz'. Supported languages: ar, da, de, el, en, es, fi, fr, he, hi,
it, ja, ko, ms, nl, no, pl, pt, ru, sv, sw, tr, zh

The same happens for:

• kk
• kz

Why this is confusing

From a user perspective, both the hosted product and the open-source release are presented under the
Chatterbox / tts-v4 umbrella, so it is natural to assume that if kk-kz is supported on the website, it may
also be supported by the OSS multilingual model.

At the moment, the OSS README lists 23 supported languages, but there is no explicit warning that the hosted
product supports additional locales/languages beyond the open-source checkpoint.

Request

Could you please clarify this explicitly in the docs / README?

For example, something like:

Hosted Resemble tts-v4 language support is broader than the current open-source ChatterboxMultilingualTTS
release. Not all languages/locales available in the hosted product are available in the OSS model.

That would save users a lot of time and confusion.

Reproduction

Environment:

• official resemble-ai/chatterbox source install
• ChatterboxMultilingualTTS.from_pretrained(...)

Tried:

• language_id="kk"
• language_id="kz"
• language_id="kk-kz"

All were rejected as unsupported.

Expected

Either:

1. kk-kz is supported in OSS, or
2. the docs clearly state that hosted and OSS language support differ.

Actual

Hosted product offers kk-kz, while OSS multilingual rejects it.