It appears there are no more secret doors in the higher level game, at least for most of us. True seeing is not finding them. The trappers I have grouped with can't find them. So for all practical purposes, secret doors and the options they contain no longer exist. That is a lot of development time that was removed from the game. It would seem you wasted a lot of time making secret doors with optional objectives behind them if you are simply going to remove the ability for most groups to ever find them.
I get that finding secret doors was too easy before. Too many people have clickies and could find every secret door. But true seeing should still be able to find all secret doors. It is not some level 1 spell but rather the ultimate spell of its kind. It needs to be able to do its job.
My party ran the Reign of Madness chain tonight and we could not find any of the secret doors through any means, even with a trapper in the party. It is not even an epic level quest pack.