Since terrain reversion was implemented I've encountered a few problems with it and building work from dead tribes, the terrain reverts to close to walls, building etc, so much so that it can create a rather deadly trap that you can't unstuck from.
If the tribe lowered the terrain then as it reverts around objects it creates a steep slope, anyone falling down it get's wedged against the object and can't unstuck out, as it registers the object your wedged against as being in the way.
Wedged like this you also can't select anything, so you can't even dismantle the object to get it out of the way.

It makes it a rather PITA to dismantle dead and forgotten structures to clean up the landscape.