In the level Kindergarten, there's a flaw in the game's design that requires you to place a wide curtain in a room with no valid windows. This renders 100% completion impossible. I'd like there to be an exception in the rules for this bug

Took a look and it does seem like the back right room has 2 windows but wants 3 curtains installed. I will put a note on the rules for 100%

that's not the issue, presumably you'd place the wide curtain over the sliding door, but you're unable to place any wide curtains in that room.

The issue I believe is a speaker on the ground that is obstructing the placement of the wide curtain, just move it and you can place it without problem!

is there really a speaker there?? i didn't spot it if there is! i don't know why that would obstruct the curtain, but i hope you're right.

I just 100% it, so no problem. Yeah, the speaker falls down on the floor when you sell the desks.

Triple checked and it does look like the speaker does block the wide curtain for placement. I will go in and edit the rules again.