Glad you liked the art and the card mechanic! The drawing took the least amount of time actually lol.
Initial idea was to keep the idea behind the symbols and cards cryptic and allow the player to pick up their meaning over time, but I agree that it just ends up being confusing. Turns out trying to make something cryptic, but also read as intentionally cryptic, is much harder than just slapping a number in place of the symbol.
I do wonder about the bug.. It should give you a message if you were trying to do something without the energy to do so... I will look into it.