I have a 2015 Wagon and it was possible to ge an almost perfectly flat floor with the seats folded properly. Sometimes the seat latch doesn't quite hit cross bar to lock in the folded position and that could cause the seat to stick up slightly. But lifting it back up and pushing slightly forward or back as you push it back down will get the latch to hit and lock.
And 250# should be no problem in most instances. The only real weak spot was the "flip over" section that spans the gap between the second and third row seats when folded. Too much of a point load in this area could damage the relatively unsupported panel. The rest of the panels are fastened to the seat frames and seem much stronger. Although in the end I ended up removing the seats entirely, I do think the TC has one of best implementations of a flat cargo area for a vehicle that still has rear seating. The operating sequence could use some simplifying but is still very quick to switch between passengers and cargo. And if you ever need to remove the seats entirely, it's just undo 4 bolts per seat base and lift out. I did it in under an hour and most of that time was spent trying to manhandle the second row out by myself. With a second set of hands, easily under 30 minutes.