Questions

In that case, where does the "rank A+" come from?

Testing in Easy mode.

rB didn't make the Easy-level girgashiy kneel, while rA did.

With a single spiker, at any rate.

If you can't get the Normal level to kneel, I'd recommend doubling back to Easy and verifying the requirements there.

Yeah, that'd be good to verify again, but... Hard to double back completely, without skill untrain capsules, though.

See about finding a rB spiker and see if that won't make Easy Girgashiy kneel.