Check card buttons now work. Each player gets to check cards individually so I changed the yellow highlight for both to now be blue and red shown in the screenshot. The highlight will not jump to an opponent’s hidden card but can show you what your hidden cards are. One thing I haven’t done is do anything when both players have the same card highlighted. Currently the blue one just overlaps the red completely.
What’s next: Addressing the same card checked issue and then doing the opponent confirm button when you play a spell or attack something.