I’m not a forum moderator, but I am one of the administrators in the official Microsoft Flight Simulator Discord server.
In a perfect world, I’m sure it would be very easy to allow multiple languages on the forum, or our Discord server for that matter (which is also English only), however, we don’t live in such a world. A lot of context can be lost in a translation, context that might matter for a complete understanding of what a user is trying to convey.
There are already several examples of people doing their best to bypass content filters on here, words and phrases that have been blocked because they’re hurtful, derogatory, and serve no other purpose than to harass or demean others. The job of a moderator is to filter out these words and stop people from creating such an atmosphere in the community, make it a good place to be for anyone regardless of their background.
If we were to allow everyone the ability to use every language imaginable out there, we would also need moderators capable of understanding every language imaginable out there, because languages are very advanced and can be used in ways that might not seem obvious if directly translated. For the benefit of everyone, and especially those that moderate, it has been decided that English should be the common language for everyone to use on the community platforms for Microsoft Flight Simulator. That way, those that speak English as their first, second or even third language can utilize that, and the others that might not be that fluent in English can make use of client-side translators.
I’m not a native English speaker myself, but I understand why the communities I frequent don’t allow me to chat in Norwegian.