Thank you for the feedback!
I think you're making a good point that I didn't realize myself! From the playtests I did it seemed that players slightly preferred learning how the enemies themselves worked - but I didn't take into account that the player doesn't really get the opportunity to experiment with how enemies work. Letting the player learn how the enemies work should feel rewarding, and although I'd like to assume it does at the moment, you are definitely right that the player shouldn't have to put themselves in a worse position to lose something - or, at least, lose something significant. In later rounds, just trying 1 enemy on a level can already be very dangerous. And, well, that's assuming that the player figures out how the enemy works in one level.
I did consider making tooltips at first, but if I were to iterate I do think I would like to still give the satisfaction of learning how an enemy works. Maybe by putting them in a situation where losing isn't as significant - maybe some alternate mode with pre-made levels and a pre-made list of enemies, where the objective is just to complete the level, and failing only resets the current level. That would be a completely different mode, though. This is good food for thought though, to say the least!
Again, thank you for the extensive feedback. This was definitely a blind spot I missed so I'm happy you could point it out for me!