I finally remembered to try mine out in hopes of helping a bit more here. For the record, it's a July 2017 100D. IIRC, this was not very long after they switched from pedestal to bench.
First, a relevant segue... Not too long after getting my 100D, the third row seats wouldn't always pop up when I hit the buttons, so I'd have to hit them two or three times. Pulling up on the seats while hitting the buttons wouldn't. make a difference even though you could hear the mechanism actuating. The service center told me they had to tighten the cables that pull the release latches. More recently, the third row seats have stopped popping up on their own at all, so I always have to pull up on them when I push the button. So long as I'm pulling up when I hit the button, they pop up every time. I asked the service center about this and they treated it as normal. To be clear, by "pop up," I mean maybe a quarter to half of an inch at the shoulder. My theory is that the cushioning in the seats has compressed over time since they are always folded, and that's why they don't do that anymore, i.e. it was never by design. This story has two points that I should have shared earlier:
- The electronic releases use cables to actuate whatever mechanisms are involved (at least in the third row, presumably in the second row as well).
- The electronic releases only briefly actuate said mechanisms; afterwards, the mechanisms can theoretically move back into their secure position.
That having been said, with my second row driver side bench section all the way back and the third row folded down, I pushed the rear-access button and the seat slid forward a bit before it tilted forward. To be clear, it didn't slide on its own, I was pushing it forward. I think maybe I always do that, but it is something I picked up subconsciously and hadn't noticed. To me, this confirms that seat position alone shouldn't have an effect on how that button works. It may also explain the differing behavior
@Bigriver is seeing where the seat folds flat (maybe it will only fold flat using this mechanism when all the way back and the seat isn't being pushed forward). Interestingly, when I pushed it back, it went all the way back; it usually seems to stop further forward than where I had it when I released it (again confirming my earlier suggestion that I've never tested this from all the way back). This may mean that the mechanism is supposed to remember the position where it was released from (because the sliding for ingress/egress is not tied to the sliding for position), or there may be a few set points that the position mechanism will attach to once the ingress/egress mechanism is triggered.
Considering my third row experience, I couldn't say with 100% certainty that the seats are designed to slide before they tilt, because if two cables or cable segments were involved, one could stretch different than the other, but I think it stands to reason that they would need to work this way in order for them to slide while the electronic mechanism is still active (so the sliding position doesn't re-latch). Otherwise, by the time they lock into the tilted position for sliding, the sliding mechanism could have theoretically re-latched. It is also feasible that the sliding position cannot be latched once the seats are tilted, in which case tilting could occur immediately without negative repercussions except in the rearmost position (if the aforementioned folding option is by design).
There is one other thing I notice with mine that makes me nervous every time because I once saw a thread where someone's seat got stuck in the tilted position and had to be replaced. That is whenever I am sliding them back, they often seem to stay stuck in the tilted position after the sliding position has latched. I then push the back forward an back a little to get it to release, and it has always worked, but I have no idea if it's normal / intentional. Perhaps I'm pushing on the cushion instead of the shoulder when sliding them back and they're engineered to be pushed/pulled on the shoulder. Regardless, mine have worked pretty consistently for 60,000 miles over almost 4 years, so hopefully they continue to.