Do your players still telegraph when they have a Capture Spell Card or playing Satori and want to copy someone's spell card? In my experience people forget what the bombs do and you can tell when they are about to copy someone.
In our case it was more like that the player of Nitori first played the Capture Spellcard and THEN looked around what to do with it. (And only after he had decided I laid down the bomb.

)
In Satori's case, I think her player never got a Spell Card (until the very end when it didn't even matter any more).
But still, I don't think any of my friends remember the Spellcards just yet.
What are your thoughts on Nitori? You've had several games with her it sounds like.
Nitori is a tank. And a great one at that. From what we've played, nobody wants to attack her, leaving her with a great health advantage.
Especially early on, Nitori will see (next to) no damage simply because you don't know what role she has anyway, so you might as well take down some other characters.
Of course, if the players aren't so stupid as to destroy Mini Hakkeros instead of stealing them (I admit that was a stupid move on my end), she might not be that much of an annoyance. But if Nitori is lucky (or rather anyone in her range unlucky) with the cards, she's really difficult to take down.
She's great in the way that you
need to adapt to a new strategy in order to deal with her, especially if she acts as a shield for the heroine (as in our last game).
I wouldn't say that she is broken, as she lacks in the offensive department. But you don't really need offense in a free for all when everyone is killing each other and leaving you untouched.
So, really, I would say that Nitori is one of the better characters. Either that, or we just have bad luck or plain suck at adapting a style to deal with her. xD;
I would really like to play Nitori at some point (but since we draw the characters randomly, it was a miracle both Nitori and Reimu came up again to begin with), but knowing my luck, when I get to play Nitori, Cirno will end up sitting next to me. xD