Hello, thank you for your feedback!
I can certainly see how they could be confusing at first, it's a great suggestion but the invisible walls are setup with colliders and I don't know how I could set that up in gb studio as I'm quite inexperienced.
If the walls were actors with specific collision boxes I could see how that would be possible by comparing the position of the player and the invisible actor and changing the position of the player relative to their own position, essentially knocking them back.
Besides that I can't think of another way of giving the player a visual cue that there's an invisible wall, at the moment at least.
But I'll keep this feedback in mind for future projects :)