If you're not collaborating with the users said (Gobuta, Milim etc.) I would reccomend not using them on the diff names that way (XX's DiffName), as it indicates they're making guest difficulties. If they're the ones making GD's, add them to tags.
Difficulty names in a beatmapset must be clearly progressive and accurately indicating of their respective difficulties, with the exception of the highest difficulty, and the highest difficulties of each game mode with a similar level of difficulty, applying only to Insane and Extra difficulties. So considering your spread you can keep different names of last two diffs atm (6.48* and 6.61*), rest should be fit to usual naming standards. (Easy/Normal/Hard/Insane/Expert/Extra/Extreme)
I would still reccomend mentioning difficulty indicating titles for these diffs, like "Extreme: Veldora" and "Extreme: Gobuta"