There was!
I'm afraid you'll need more than "There was!" if you want to prove your point. Bane barely showed anything new after that. He knew the Force Storm, a few rituals, and learned a thing or two that inspired his Rule of Two. We didn't see much else in terms of improvement though.
There was some evidence on his power.
Point out a time where I said there wasn't. I don't know where you managed to get "There was some evidence of his power" as a response to "We don't know the specific reason why Bane 'worships' him. There could have been several reasons". Obviously power could have been one of the reasons, but you haven't addressed the point I was making (Despite power being a possibility, it isn't much more valid than half a dozen other possibilities).
Didn't Bane trigger the collapse?
Not as far as I can remember (I haven't read it recently though). IIRC, his attack was intended to kill Kas'im. The temple collapsing around him as a result of the blast was pure luck on Bane's part. If not for that, Kas'im would have wasted him. Bane lost any real advantage in that fight once Kas'im stopped "pulling his punches" so to speak.