XenForo does not support content in multiple languages. If you want tagging in multiple languages then your best option is to use multiple installs. In my experience if you combine tags across multiple languages you will end up with a large mess. Especially for the languages that you mention, because these use very similar words for the same concepts. This generally confuses a lot of people.
Alternatively you can also decide to turn off tags in the forums for other languages than your main language.
That indeed is something, but if multilingual content implies that you can have data sets per language. i.e. have the same notice in multiple languages. Have the same tag in multiple languages. The same node in multiple languages.
The way Xenforo is currently setup it does not cater to host multiple languages from the same installation.