I have been playing Stonekeep for years, but there is a question that eludes me. What happens if you go to the end of the game after being mean to Wahooka? I read online about having to do painful backtracking at the endgame.

You can still win the game without him

Wahooka isn't essential to win the game. He just gives a couple of hints that you can get from other sources. In the worst case scenario - you just fight Shadoking by force. And you can defeat him.... he doesn't have a death animation though.