The US court orders something to be produced. If MS declines to produce it, then they are in contempt. MS's internal structure isn't of interest.

(Assuming the US court claims jurisdiction, which is more or less what this case is about)

Is it really an "internal" structure though - Microsoft US and Microsoft Ireland will be different legal entities. Of course, Microsoft US as the owner of Microsoft Ireland can tell their subsidiary to do something - but that doesn't mean that the management there will do it if it is illegal.

Presumably there is a way to challenge this though. If the court ordered Microsoft to produce a square circle could they still be found in contempt for failing to do so?