any news if the improved initiative feat bug will be addressed?

If there'll be a new patch it quite certainly will. If not, it won't, unless Ex makes a patch for it.

Improved initiative is a feat which is as all other feats - hardcoded (inside exe file).
Unless there is a BG2 effect inside IWD2 with something similar to II, there is no chance to make a 3rd party patch about it. Patience.