Thank you for the reply, Chocobeau. I don't have the option for 'custom,' perhaps because I'm on a PS4 server. But if Heremtic isn't on PS4, sounds like it'd solve the issue for him.
I reset the config and levels are normal again, even after editing a few things. Can't get ShowFloatingDamageText to work or ForceAllStructureLocking=true to work. Tried both with ?, b and without either. Or, at least, it's not working on storage boxes and a smithy.
I just got a server and, without having touched any of the level settings, the player cap is 85 on Aberration. And I can see in the ini files that there seem to be levels up to 115 (I assume to compensate for the 'minus 15' bug), but I'm still stuck at 85.