Yes bring back the Tahitian Terrace! This would greatly benefit the area as aladdin does not quite fit the theme perfectly although aladdin isnt terrible. I would like to see the space used as an intimate sit down restaurant themed to the island/polynesian vibe that the tahitian terrace had.
But to the original question...I don't think adventureland really needs to be fixed at all (except for minor aladdin's oasis change). Even with the under used aladdins oasis, it is one of the best areas in the park!