I don’t want to question your words, but 1600 renderings, scripts, text animations for 1 person in 3 months, as for me, this is not realistic if he is not a robot!
considering ren'py work, process may take a little longer of course. But not so much, it is pretty simple engine. And as far as I understand, several people are working on the game, dividing tasks.
we can also compare this update with the previous one. Almost the same development time, but a significant difference in quality and quantity. Devs can do more in a shorter period of time, but for some reason we received the last update the way it is...