The letter is most likely the only change made.....
Actually the tutorial was updated and it's modes work now. There is an additional outfit for the tutorial. A new hidden achievement, which allows additional points for more outfits for the tutorial girl, Sonya. Bug fixes too.
It was 2 weeks from 0.1S to 0.1F, with some overhauls and bug fixes as well. Content wise, it was mostly all tutorial work to complete it's mechanics and functionality. There will still be refinement to it as the game progresses.
You also have to keep in mind the developer helps patch Ren'Py too and has found multiple bugs in the engine. Being that I follow Ren'Py's github, I can easily tell you none of the other VN devs doing lewd games do this.
I think it's important to remember that supporting the community of independent game developers allows for more choices when you go to play games. There's literally no reason to be negative unless you are a developer doing the work and can comment on the level of effort it takes. Although comments about slow development from long term Patreon's and any negativity that comes from this is completely understandable.