Just finished my first fallen spire campaign finish.
Warning: Minor spoilers ahead.
I gotta say, I was less than impressed at the final AI push. I mean yea, they did throw out all kinds of golems and stuff, but it wasn't enough to even begin to scratch my chokepoint, and the rate they came was far too slow. And there were no hunter killers, ever, due to spire based exo waves, including the final push. (I got one in a spirecraft hard exo-wave once, though)
Needless to say, when the exogalactic transceiver (or whatever it is called) was finished and the allied spire fleets started coming in, the AIs puny force barely scratched their forcefields, much less their health (dang, those Mk. IV heavy beam modules are stupid powerful)
The only thing that began to resemble a threat to them was when they showed up on the first AI homeworld, where all the stored up "defense" exo-points were unleashed and a whole hoard of hunter killers were spawned. That would of done some nice damage to the fleet, except that they decided to get hit by the "I'm just going to sit here and do nothing" AI bug after firing a few shots. (I have a save of this, but haven't gotten around to making a mantis post yet)
Granted, this was on difficulty 8 rather than 9 or 10, but still, I expected more. The AI may be a little too aggressive for even the spire fleets in its final push at 10, but they are barely even trying to take me out at 8.
If you want a save of this underwhelming final push, I have some of those as well.
Still, I had great fun with this campaign. Before I got some of the higher level spire starships, the AI did put up a good fight, and that was fun to figure out how to deal with.