The main issue I see with creating new categories for other languages is that it wouldn’t be easy to moderate them unless the moderators of the forum are able to understand the language of each new category (e.g. Chinese, German, Spanish, French, Russian, etc.).
It would help a lot if Discourse had the ability to have “category-specific moderators”. that way we could assign moderators to specific categories. there has been discussion about adding this feature to Discourse (e.g. see this topic), but it hasn’t been implemented yet.
How about creating new Riot channels for each language? right now we have #safenetwork:matrix.org, but we could also create other channels such as #safenetwork-de:matrix.org (German), #safenetwork-es:matrix.org (Spanish), #safenetwork-fr:matrix.org (French), #safenetwork-ru:matrix.org (Russian), etc.
that way each channel can be managed independently. one or more community members (who speak the language) can moderate them.