Anyone ever bought music from these people?

Grey area. With editing they're -I think- referring to fades or c/p'ed sections of the music. What you can't do is change the actual notes (if that would be possible) or perhaps add your own notes as an extra layer.. dunno.

I do wonder whether pitch-shifting counts as changing.. In some cases -a smurfgame ?- you'd want quirky/pitch-shifted music perhaps.

Best is to just contact 'em about all that..