The demo I've played of PCB was extremely different from the final. It had only MIDI, all the character sprites were different (which means it probably is the same one we've played), and the danmaku, while mostly the same in design, was very...rigid somehow. Like the game was just a rough prototype of the final. The cherry system, to put it simply, didn't even make supernatural borders.
Then there was the demo before that, which doesn't seem to be anywhere on the Internet. According to the wiki it had many spell cards that were removed entirely from the final. BV
I do agree that this demo is pretty buggy. To be fair to ZUN, with the earthquake situation and him needing to conserve power he probably hasn't had much time to bug test it even with the extended time.
EDIT: @the spirit situation, I think that risk was intentional. It seems that ZUN's idea behind this game was to tone down the difficulty and put the difficulty in scoring. My only complaint with the system is that it's too difficult to gain extends. Since ZUN did add the life fragment drop at the end of bosses in UFO between demoes, maybe this will be addressed in the final.