Two of my test levels require coop mode, yes. This is a fairly trivial problem though: you just host the level, type /gamemode coop, and then /r so it loads properly. The main issue with these levels is that the first test in them can get frustrating with lots of players, but I can solve that by simply editing the level (adding multiple copies of the first test would do the trick).

I have a few other tests, and they work in CTF. Parts of them could also be added to another level.