Yeah, the level select screen had a minimum of time and thought put into it; definitely needs to be more obvious that you click the level text. There's a reason we've put that in four separate places now >_>. Having it be keyboard controlled would probably be even better, although my wildly optimistic projection for post-jam is that there's so many levels that scrolling through with a keyboard is a chore.
The tile inversion attack is definitely not supposed to stuff out matches; that'll probably be some kind of race condition bug. The tiles themselves, though, are in a weird spot. Some of the later levels DO take advantage of the tile inversion by having triggers on one half of a pair but not the other, and...well, originally they were placeholder dev assets and I then found that while playing them increased the demands on the player's attention since you have to focus on differentiating them, failing to do so and messing up a placement felt frustrating but in the same way Seija screwing you over in any other way felt frustrating. That plus time constraints plus the levels that needed them made me ultimately decide to see how leaving them in would go, and I think they're just "part of the game" now, for better or worse. I might be doing a couple updates post-jam (at a minimum to make it obvious how to start playing ._.) but ultimately I don't think I'll be changing those.
You are absolutely not wrong that doing that essentially breaks a cardinal rule of match puzzler design, but if there's a place to try doing that and see what happens, it's a game jam game.