I'm not feigning ignorance of contract law or copyright issues with my argument. They definitely did not have their respective lawyers go through their paperwork as the project was imo informally/casually planned. If so, there would have been proper contract validity tenures, renewal terms, dissolution clauses.
I'm assuming since the dev, Joanna didn't want to be shelling money out of her own pocket for Javier, they agreed to some sort of partnership. The entire deal clung onto the fact that Javier would not have "issues" moving forward.
In this case, the dissolution clause would have worked in a way such that if Javier (or Joanna) decides to terminate the partnership prematurely, they would ideally have to forfeit their share granted that the income they've received was over $xxxx. Why? Because the project faces sufficient downtime and a very long pause in the process of accomodating for a new developer/designer.
I'm not taking the dev's side either but in this case, its clearly Javier in the wrong. The downtime (due to this whole fiasco), extra expenses (I assume Javier is still being paid a % of earnings for the work on C5), and the fact that Joanna now has to pay a second designer out of her share to re-design the entire game all sums down to one thing - Javier terminating the contract prematurely and using his share as a bargaining chip to ask for royalties of a project he willingly chose to leave, knowing that it would cause serious downtime issues for the project (and revenue issues, you can just look at the drop in patrons due to the inactivity).
So yeah, not going to explain further but you can thank Javier for the fact that this project's last update was half a year ago. By this time, C6 would have been released and C7 would be in development.