Apparently Steam page says its "reworked generated art"
The generations were used to help with styling/shading (especially learning the style, anime styles like this are hard to learn) and poses, but every CG had hours of work from a single artist (who developed this game from beginning to end). No artist was replaced as such, you can see it in the CGs of the game, a ton of details have been reworked to match consistency and there aren't classic generated images issues with broken fingers and unnatural details.
Artists also often rely on 3d programs like Blender for the pose and other details that are hard to mentally visualize, and generations were used in exactly the same way because there isn't a single CG in the game that came out that way generated.