When I first played the mirror game, I, for some reason, thought the game wanted me to paint a picture so I just drew a silly smiley face. I was half-expecting a gag where the drawing would appear on the finished mirror, lol. I forgot to mention that in my original comment. As for making the painting game more engaging, maybe you could make it where you can accidently color outside the edges, but you get more coins if you don't do that. That would add some tension as you try to fill the edges in time but you don't want to lose coins by going over the edges. Maybe it could be justified story-wise as wasting the reflective material and having to spend gold to replace what you wasted.
If I were to offer a suggestion for the Runes minigame, perhaps you could add sounds when the last few ticks of the timer are happening? During the last five seconds, each second makes a "tick" sound to signal that time is almost out. Maybe the number could turn red and grow bigger as the timer runs out to really emphasize it. If you implement a cooldown in-between, maybe you could include some sort of animation, such as one rune sliding off screen as another slides on-screen, for example, and this could act as the cooldown period in a way that would feel natural. Maybe that could work?
Good luck on your project!