Actually, there are some modifiers in the game for particularly difficult locks/traps/pickpockets. For instance, there may be a particularly difficult trap that has a -40% modifier. If you have 100% in Find/Disarm traps...your thief is now down to a 60% chance of successful finding/disarming. So...you may want to beef those up a little.
In my party, Imoen has a modified 125% Find traps and she fails occasionally. Kind of irks me as she's my only thief right now.
I'd suggest dumping some more points in your major abilities and beefing up your Detect illusions. This can be a real useful ability if you don't have True Sight via a spellcaster, item, or an Inquisitor. I think that set traps is the best it can be at 100%, but don't quote me on that...
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Now where did I leave that doughnut?!