Can this also be translated as "When will you build this school"? or does Kapan only refer to the past?
I think that needs to have "akan" in it, but I'm not sure
Yeah, since the question isn't moored in time via a specific tense (which Indonesian doesn't have anyway, but only aspect), it could mean that, too.
A better translation for "mendirikan" than 'build' (membangunkan) would be "erect".
That is, the example should read: When did you erect this school (building).
Or: When did you exstablish this school.
Erect is the most literal translation, but I think build is close enough to erect to be acceptable, and without any unfortunate "teeheehee" elements to it. Establish is the best choice IMO
Can this sentence also mean "When did you found this school?"