I think the problem is a lot of the best foreign spinners are from the sub continent and just don't know how to take advantage of the bounce. Although even someone like Kumble who used bounce much more effectively than most spinners did great in India and terrible in Australia so i'm not really sure of the reason.
Can't say he's been terrible to be honest. In his first series there he was definitely terrible (avg 90) but the two series after that, he's been pretty decent (avg 29 and 34.5). Not exactly a strike bowler like Warne but serviceable. But yes for the most part Kumble has only been really effective in India (not even all of the subcontinent).