Wiki Translator is a volunteer based role, like almost every other role on xat.
Anyone can apply and potentially become a wiki translator. To submit an application go to: https://apply.xat.wiki/translator
We don't really have many requirements, what you need is basically a certain knowledge of the English language and and a deeper knowledge on the language you're willing to translate.
Obviously there are languages like Portuguese where we have 4 people who translate the wiki, so there's no room for a new translator for this language.
Other than that, we're really open to letting new people in, as long as they're qualified.
Regarding "updating the team", we can't really do much about this other than inviting qualified people we eventually know (when there are any) and reviewing applications. To be honest, there are not many people actually willing to dedicate their time into translating our wiki and when there are, most don't meet our requirements and some of them are just poeple who want a role on xat at any cost.