Thanks for playing and leaving your feedback!
I apologize if the colors gave you trouble. I'll make the board and tiles easier to see, and I'll also add a proper outline around highlighted tiles.
That swapping behavior is intentional since I ran into a few cases where making a match was impossible. I may write logic that will prevent those cases in the future, but that would have taken too much time to add during the jam.
The missing letter is a web issue. It's actually a newline ("\n"), but I have no idea why it renders the way it does.