Thanks for such a detailed opinion! I feel like most of the things you said would have been done if we didn't have a time limit.
Also, for the invisibility, it was actually made on purpose so It would also be difficult for the player. In the actual project page of the game (Messy Infiltration by Hashiro (itch.io)), the description says "The stealth suit is damaged as well. It works... kinda. When activated the enemy Guards won't see him, however... we also will loose visual on our Operator.". So that was the idea from the beginning.