Is it allowed to use older versions of GD before 2.206 to make LiveSplit work?

Yes.

@MadysonWeissnat Using 2.204 allows you to use the autosplitter which removes load times (and considering LRT is the main timing method for this game, it's definitely an advantage).

The autosplitter got updated to 2.206 FYI.

@Walgrey Ok, thanks for the information, I wasn't aware of that.