I think the main problem is project management. There's just so much already in there that if it's just slightly too spaghetti it's gonna take extra work to have new stuff fit. Maybe SR7 is being slow with providing assets but I think it's more likely the code side causing delays.
I'm speculating.
Even if he's not using template/proper tools and doing it manually, there's probably a scene/file he duplicates (wondergirls are EXTREMELY SIMILAR on their timings/dialogues), probably just updating bodies/heads/mouths per scene should be the longest to do by hand (and exporting per layer from his photoshop's file by hand).
Redoing spaghetti each time would be a colossal waste of time, and shouldn't introduce bugs on previous content.
The rest (like unlocking the cells) is meddling with the current code and something already done for the past 6y. If after 6y you cannot read your own mess you have a problem.
There no "new" dev features (like a new event like yacht/prison), it's already a copy/paste of present content. I could understand a report for let say an update like the Casnia event (and the FULL one, beaucuse it's a new "spaghetti" to develop/debug with its own specifics issues), but not with so little content, similar than what's already done.
I could understand a bug with let's say Roulette since it's a new dialogue unlocking stuff on old code you haven't touch in a while, I cannot understand bug on new content you encounter THE VERY FIRST TIME YOU PLAY IT.
There's no tracking/planning of what he's doing. If so, he wouldn't update the cells up to 32 and let the vault with only 3 slots available...
He's clearly adding characters cells to milk, because it's the easy thing to do (and remember, no leash for the new characters, and MB is not updated for the vast majority of the cast), and either work sloppy/don't want to integrate his art in the game and wait until the very very last minute.
This guy want to do art, not making games, which I can respect that. But for the amount of cash he could afford a proper dev and be little more respectfull to his patreons.
Ho wait...