I think the issue with Damian will be solved in the next game and I believe they didn't choose to concentrate to much on him, because D:OS2 wouldn't stand on it's own feet otherwise (I guess they became careful after Divinity 2).
The thing about Zandalor is a good point, I didn't knew that.
As for the rest of the timeline: Yeah, it is a bit hard to differenciate what it was, but I guess, we can put The Wizard Wars and Sourcerer Wars into the Lost centuries (as you can read about here:
http://divinity.wikia.com/wiki/Timeline ), but maybe they will clarify this with the next game?
