Yes, it’s a good question, especially since these aren’t the only two languages spoken in the region. I suppose the idea is that the language of wikipedia would match the language of name on each feature, but it would be tricky for features that have mixed-language name tags. This is probably why some wikipedia:xy usage remains, apart from the recent mechanical edit in Israel. My point is that the documentation could say so explicitly, if that is indeed the reason.
In any case, the potential for linguistic conflicts is one of the original arguments in favor of Wikidata, which is language-neutral. I would encourage any data consumer to consider processing wikidata or at least use Wikidata to transform wikipedia into the end user’s expected language, as applications like OsmAnd do, rather than relying on the language to be tagged explicitly in wikipedia:xy and using that verbatim.