Ok, a few more results after a horrible day at work.
I took two wild boars, male and female, and locked them away in a room with floodgates. Just outside the room I built a line of cage traps. Then I placed another line of floodgates. After the one wild boar reverted to wild state (and killed everything else in the pen), I built a new line of cage traps past the last set of floodgates. Both boars were trained masterfully. The boars reverted one stage at a time back to wild, each time they dropped a level, they gave an announcement about forgetting their training. The first stage of cage traps were built before they were placed in the pen, and the boars were walked over the cage traps. The second set of cage traps was built after they went wild, to test if they were trap avoid, or just were aware of traps they had seen while tame. The wild boar ran over both sets of cage traps with no issue. The female boar had two piglets while in the pen, they were still trained at a medium level while the two older boars were either basically trained or semi wild. I do not believe either piglet lost any training levels.
Conclusions:
Animals that revert to their wild state avoid all traps, both those they saw when tame and new traps.
Animals revert to a wild state one stage at a time, semi-wild being your final warning.
Young animals either do not revert at all, or revert much slower than mature animals.