I don't think they're crawling. Else everyone would have movement penalty and ranged users would have an advantage.
Also, this game has weird bugs not fixed. In vents, my guy just stopped attacking, despite full AP, no buffs, just refused to shoot normally or use ability. Only solution was to lure the enemy away from the buggy spot, only then everything started working properly. It has happened to me before in the caves. Luckily it doesn't break the game.
Also that game start issue where game starts in borderless window view forcing to alt+tab twice to make it go fullscreen. Weird.
Also, is there an easier way to break rocks blocking areas in caves or everywhere else? Like dynamites? Maybe we get a drill or something similar later on? I have not bothered attacking them all, but I'm guessing they lead to secret/new areas. I found secret areas cause of perception only so far.