You probably won't see the help center translated into other languages until Stack Exchange hires employees who are actually native in those languages (or a user native in the language translates it and hosts the translation somewhere).
Having said that, I want to clarify that there is a big difference between a site about the Arabic language and a site in Arabic. The Area 51 proposal is about the Arabic language, meaning that in general questions and answers will still be narrated in English, talking about the Arabic language. This is exactly how the Spanish SE runs - very few questions are written entirely in Spanish. The same can be said about the German SE, which does have a slightly higher percentage of solely-German questions (but still not a majority) and, unlike the Spanish SE, actually uses English for all its tags.
The Stack Overflow in Portuguese site is the first of its kind. It is a full alternative to Stack Overflow entirely in Portuguese. Meaning that English is nowhere to be found on that site (except maybe in code for that particular site). Since the only spoken language there is Portuguese, they kind of require a help center entirely in Portuguese, and Stack Exchange hired an employee specifically for handling this community. They couldn't have done it all without him. They're also currently hiring Community Managers who are fluent in Spanish and Japanese, likely for similar purposes.
Note: I'm only pointing these things out to give you a better understanding of what an "Arabic Language" SE site would actually be. While I agree having the help center translated into other languages related to a particular site, there will likely be a lot more English on that site than you're expecting. It certainly won't be entirely in Arabic.