Okay, Largenuggets and I had our meet and went over a lot of things. Here's a brief explanation, which I'm putting into a larger post that includes prize spread:
We're putting all scores in a spreadsheet. The first way we're sorting is by series records. All 4-0 players advance automatically, and probably all 3-1 players. We expect to fill out 16 players at the bottom of the 3-1 players or the top of the 2-2 players for this group of tournaments.
The first tiebreak form proposed by Largenuggets is to give favor to someone who attended a second event (which I don't necessarily agree with), and under that we have points difference - this is measured by individual games won/lost per series. If necessary we could look at their relative rankings as well, but things like Buchholz cannot be used (easily) when more than one event is involved.
This is a proposal right now, and we're checking for some player feedback over the next couple days before we lock in these rulings.
Bigger post on the way. Will edit this post when it's up. There will also be a Steam announcement, in-game notice, and social media.