I haven't opened up the source code, and have no experience with RenPy as an engine, but a little bit of Python experience (ML, mostly) but once you start hiring people to do things, then your expenses on a game increase dramatically.
And when making a game in Python, who give even half a shit about optimization? If you cared about optimization, you wouldn't build it in RenPy. I like the story of Harem Hotel so far, and you are probably right about their code being terrible. Their code doesn't have to be good for his story to be good. Go look at the code for Undertale and see if that dumpster fire stopped it from being a good game. It probably also kept it from having any expansions or anything, and yes, Runey might be shooting themselves in the foot by making things in a sub optimal way, as far as maintainability goes, and it will probably delay updates coming out.
But long term, as long as the game still gets updates, and they continue to communicate with their community, they continue to get paid. Hiring a programmer doesn't really help, as it would be a large drain on resources, while also eliminating some of their long term income. As a consumer, I'm willing to pay $25 for a game once, but not $5 a month for 7 years, but enough people are, that option B is a viable model for a game creator. So the code will probably be rage inducing for a long time to come, because there is little benefit to the person who can fix it to do so, and no benefit at all to hiring someone, even on a temporary basis, to fix it.