kokai, you should know that the game is currently under development, there is an update every two weeks and the game still isn't finished
1. You can't progress because you've run out of events - as I said, the game just isn't finished, be patient and wait for the updates
2. If it says "Sorry that item is not in the game for now", well, it means that the item is not in the game... the Girls didn't add events with the item, so, as I've mentioned before, you'll have to wait
3. Sorry I don't really get it, but I highly doubt there is a bug going on here
4. Corruption is stuck at 430 because it's the limit - Morgarith even informs you that you've reached the maximum of your corruption level available in this version of the game
Summing up - keep waiting for the updates and read everything carefully