Ah, from a quick look at the INI file, it appears you haven't actually compiled the styles. I wasn't even aware they *could* be used without compiling them - so it would seem this bug only occurs if you haven't done so. I'll test it in more depth soon.
For now, I've added modifying the boundary options. So, unless there's something undocumented or something new you've added since the last release I downloaded (the one where invisible objects was broken), it now supports everything except background terrain and special graphics, I think? I've thought of a way I might go about implementing the former; while as I've said for the latter, I plan to overhaul how it handles that for Lemmix-based styles, as the way I plan to do that should also make it much easier to integrate SuperLemmini-style ones.
EDIT: Implemented the escaping for the level name. As it appears that traditional Lemmini handles these escaped levelnames just fine, and you mention it should be safer, I've implemented it on both styles.
EDIT: I also realise, there's no support for mods in the editor either, at this stage. Although you can always just have seperate copies of the SuperLemmini style sets that are individually modified, though that may be a bit tedious.
EDIT: Playtest mode implemented.