The coder started the project. The artist is the "new" guy who joined a little into book 1 I'm 90% sure. Regardless, they should hire someone. FETs code is already a mess which probably doesn't help dev times. Hiring someone to work on it wouldn't be that bad, even if they were just working on a more clean seperate branch that slowly merged into the main game. The coder's writing isn't bad at all, I reckon they could save so much time by just leaving him to write. There's no shortage of python devs that could do Ren'Py, it's hardly rocket science.
You could also have a pretty clean division of labor by hiring people for different tasks, even with a project of this scope.
Somebody could be hired to go back and work on refactoring the previous games, thus having the ability to add things like a scene replay system or fix bugs without affecting current content at all, somebody could be hired purely to do repetitive busywork (assigning sprites to image files, setting up the frames of animation loops, cropping things out in Photoshop, layering, etc.), somebody else could work as an actual full time writer just on the story's flow and the dialogue, the main coder could work on the major systems (map navigation, day/night cycles, inventory, game progression, etc.), yet another programmer could work separately on something like the CCG minigame, you could hire another person for finding/composing/editing sound effects and music, another artist could come on just to do menial, boring technical art like cleanup work, coloring, doing inbetween frames and so on, you could hire someone else purely to make backgrounds, you could have yet more people doing things that require a different style (a segment where the characters need chibi sprites or detailed splash art), or someone doing general graphic design work like making UI elements.
Where there's a will, there's a way.
