Only accepts English as expected input language

[hesstry]

There is mention of providing further context to the model through
expectedInputLanguages = langId[]
But it seems this is not yet implemented, and I am notified through error that currently only ['en'] is accepted.

Changing from expectedInputLanguages: ['en', 'es'] -> ['en'] made the availability check succeed as the error described.

[tomayac]

This is the repository for the specification, and there's no issue with the way it's specified. Implementers like Chrome may be (well) behind what's specified here. Please refrain from opening issues not related to the specification here.

If there's an issue with an implementation, for Chrome, open a new Chromium bug, but there's likewise no issue with the implementation in this case. Simply, the model doesn't support proofreading for other languages yet. That's why you have the availability() function, and it rightly said what you wanted isn't supported.