Bump.
The issue also seems to affect Component::localPointToGlobal() and Component::localAreaToGlobal() when called directly, so the root cause is likely detail::ComponentHelpers::convertCoordinate(), which all of the mentioned functions call into.
EDIT: After digging in on it, I think the problem is probably just as simple as the scale factor being wrong, which sounds like is a known issue based on this post: Juce 8 bug - DialogWindow on Windows not scaling correctly - #4 by reuk .
Is there any chance this could get looked at soon? It means a number of functions will not work correctly on Windows.