The witch sells accessory items that each give +1 to a stat, you should be able to go buy the one that has CHA, equip it, and then view the scenes (optionally switching back to whatever you had after). Failing that, if you open up your save file, you can just edit the text file itself to "cheat" and give yourself whatever stat scores you want: I've been doing this when new versions come out, so that I can breeze through the earlier parts of the game again, without having to struggle on the fights, etc.