Well, MSE is a bit of a special case: the "language" metas, for the most part, should cover their own languages. MSE's kind of the prototype for all the metas, with their own quirks. In many cases, unless it's a network wide issue, a local meta would be your first port of call, even on English sites.
If you do have a language site with a specific problem you can't solve on your meta, someone's gotta be able to write English. Work it out on your meta, mug a mod or a trusted bilingual, and get them to bring it up. If it's a broader issue not local to your site, it's still OK here.
If you have an actual problem, someone will help. We'll just have to work together to find the best way to bridge that language gap.
From the perspective of a long time user of the network (and a moderator): each additional language has tended to need a fair bit of additional resources - and is pretty intensive compared to a regular site. Each language had a native or semi-native language-speaking CM (though, for the most part, those got rolled into the main CM pool). I think there's about 11 CMs, and having four CMs specifically for languages ended up not working that well. We do still have a few native language-speaking CMs (and one person whose exact role is a mystery covering a site) for the non-English sites. Diversity is awesome, but even if we had one CM per language, about a third of the team or more would be covering one site each.
There's cultural communication: stuff sometimes would get lost in translation, even between different dialects of the same language... If there's a critical issue on the site, it's going to be tricky getting someone up to speed and looking at it.
Well, at least at the moment, I don't think Stack Overflow (the company) has the resources and willpower to do it for now.
I suppose that could change if a new language worked with the company's bigger goals. The language SOs were when folks were pushing for SO to grow, and felt those developer communities were underserved. SE's kinda in a bit of flux, and has been for a while.