Applies to both [S] Terezi: Proceed. and [S] Flip. Since mobile can't do keyboard inputs, you can't start the animation, even though it should only require any input for the game to say that you can't control Terezi, and after the first input, mobile
would
be able to close the dialog box and continue the rest from there.
This may not be a bug in itself, but it's certainly something that would make sense (allowing mouse clicks/taps to activate the initial reaction) and would be very convenient for mobile readers. Low priority, of course