Four of those could be combined, but that would complicate the code a lot even in its current state (and much more if we do some sort of caching, and need to deal with invalidation, which is different for every API query).

I am not sure there is much benefit to it; when cached, those queries should be fast anyway, and when not cached, the single query might actually be slower since everything happens sequentially in PHP, while the independent JS requests would be parallel to some extent. (We should probably measure this.)