It should be strong enough to hit both the crypt and the scoop straight on. If so you're good. There's no need for it to be strong as there are no ramps or loops for it.

From what I understand, the upper is supposed to be a weaker coil, as you thought as well, to avoid it from striking the drop targets too hard and busting the heck out of them.
A little fact I picked up from watching the TNT/Todd Tuckey video for TFTC on YouTube

I don't think mine kicks as hard as the lower flippers but like others said all it really needs to do is hit the tombstone/crypt and make the creature feature scoop.
I have my coils turned all the way up because no matter what I do the pop bumpers still seem weak but even set on high I have had no problems with busting plastic or anything like that.