Well... I could complain about a lot of things here, but most of those boil down to Tyrano being terrible, at least when you're used to Ren'Py. That said, I strongly recommend using Ren'Py.
Something that rubbed me the wrong way a little bit, is something I read here in the thread. Namely that we're supposed to know Jen's favorite food by reading the About section in the game. I don't think anybody ever does that, so hiding any information there that you want people to actually find is something I advise against.
Also, the MC's name is mentioned (I think) only once, so it took me a bit to notice that the player doesn't get to name him. I personally like to name my MCs, and I doubt I'm the only one, so I guess I'll request that feature on top of all the features that Ren'Py provides automatically.
Finally, I wasn't sure if I should bring this up, since an explanation might already be coming, or maybe it's already there and I missed it... But the MC and his sister clearly already have an unusually intimate relationship, which usually comes with some kind of explanation. Feels a bit weird not having one...