Haha, I tried picking this up again and I remapped my entire diff, then the editor crashed, every single note in the entire map disappeared, and now I have to do it again. I don't even understand how that happened, since it's theoretically impossible. Yep, maybe it just wasn't meant to be.
At least on my end the editor can't handle this map at all. I think it's the length that does it. When I try to move sliders, it crashes like 7 times out of 10. It starts lagging like there's no tomorrow and then osu! says an error has occurred. This only happens in marathon maps. Some kind of gigantic memory leak, I have no idea.
Just posting it here in case there actually are people who are interested in this dead forsaken project. I have never dealt with something more frustrating in my life. Neither osu!'s beatmap submission system nor editor was made for marathon maps, it seems. It's ridiculous.