3.1.2 Language of Parts - How do we comply for user-submitted content for WCAG 2.2 AA?

[SAGARACH65]

For a english-only app, the users can submit content (e.g. names, profile descriptions) in other languages, which can be displayed to other users. Aiming to acheive WCAG 2.2 AA

Question:
What is the expected standard for handling lang attributes on user-generated content where the user could enter anything and that needs to be shown to other users? Found a library that can do it https://www.npmjs.com/package/franc, but this does not seem to support this 100% of the time.

Are there more accepted ways for it or how do people handle this for WCAG 2.2, if we dont support this it i think we can label it has Partially Supported is that fine for full 2.2 compliance?