Yeah, the way o2jam's song format works, there's no way to properly use inherited sections. You'd have to figure out how to tell the difference between a speed change that's for effect, and one that's a legitimate speed change in the song. I'm not sure why the lines would be hiding the notes though, I actually prefer the use of uninherited sections because osu tells you the BPM range, most common BPM, and you get visual cues based on measure lines when you play the song, so you always know there are speed changes, and can read them easier when playing (assuming the measure lines don't cover your notes).
Glad you're enjoying GJ's maps. Rubythespamer/Apenix, yumel the lightbringer and FF Ken Yu all have some maps at lower levels as well (and are all pretty good quality), though I think they all have fewer low level difficulties then GJ has. Kuliner also has good low level diffs (on the ones I have uploaded, his easy diffs range from level 5 to level 13, and normals 15 to 24)
Glad you're enjoying GJ's maps. Rubythespamer/Apenix, yumel the lightbringer and FF Ken Yu all have some maps at lower levels as well (and are all pretty good quality), though I think they all have fewer low level difficulties then GJ has. Kuliner also has good low level diffs (on the ones I have uploaded, his easy diffs range from level 5 to level 13, and normals 15 to 24)