This ... depends.
We have several sites about languages (Russian Language & Usage, French Language & Usage, Japanese Language & Usage, and a few others). Those are certainly possible to put through the Area 51 process. If you're thinking of a Hungarian Language & Usage site (I see someone recently created a proposal for it), then it's theoretically doable. It might be difficult, since the target demographic might be smaller than for the other, more widespread languages, but in principle... it could work. Especially on a large site like Stack Overflow, there may be a group of users who are fluent in Hungarian or want to learn it and would be interested in committing to the proposal.
If you're talking about a fully localized size (such as, Stack Overflow in Hungarian), we don't have support for that just yet at all. We're working on some localization projects (most recently, support for non-ASCII tags), but we're still a ways out from being able to support a fully non-English site.
If you're talking about a site that doesn't need to be fully localized (user interface and all), but would like to be able to post in Hungarian... that could work. I don't think we have any of those just yet (aside from the sites about languages I mentioned above). One potential issue here could be that if your audience is non-English-speaking at all, you would run into big problems with moderation and user experience because the interface will still be in English.
And with all that said, we're also working on the next generation proposal process that should address some, if not all, of the core issues with Area 51 while preserving the philosophy that a successful site needs some sort of a base of community support and engagement to start from.