To be fair, I can understand that not getting some game to run is probably the most frustrating to those for whom this comes as a surprise and many people – not just Windows users, although they make up a large portion – simply expect random binaries from the internet to just work™, an experience that I not only can't give currently due to technical reasons, but also find somewhat concerning on ethical grounds. But yeah, you probably don't want me ranting about Windows in response to "running game hard :[" either. Quick note regarding my setup: I would have to use a friend's Windows machine for debugging purposes (already not an ideal starting point) and it has the habit of flagging a "Hello, world" program, that runs fine with a bit of Wine as a virus. It's probably detecting the GPL as Steve Ballmer intended. I would probably need a person more experienced with the Microsoft OS to help me out there, but from personal anecdote increased knowledge of how Windows works also comes with an increased likelihood of having at least an Ubuntu dual boot and thereby not being affected by this problem.
Regarding the assets, those are actually not public domain. I just checked the README again and I'm not even mentioning any licenses that would imply such a thing either, so it would appear that for once none of my assets were actually drawn from the public domain for a change – most of my other work at least uses CC0 music, but you can't get that with Touhou, now can you? Out of the licenses that do apply to the assets, ZUN's policy statement is certainly the most restrictive, but when it comes to e.g. kaoru's stuff, that actually has a disclaimer that it can't be used commercially. Just wanted to throw that out there for potential legal reasons.
I don't believe losing faith is quite as hard as Touhou canon makes it out to be, especially in the advent of the Corona virus. People still turn to God when vaccines would be more effective… no, I don't think Kanako would give up on gathering faith were it not for quarantine restrictions. While it wasn't explicitly mentioned in the text, Yukari "detaining Kanako and Suwako for their own good" was meant to imply that the disappearing of the shrine was actually her doing – she gapped the two together with the shrine as it'd be less work than contact tracing.
On the part of having no idea why or how Renko is there, neither does Renko herself – it's alluded to in the first line. Metatextually I'm using her as a gappy and player stand-in of course, but her only roommate is Maribel and of course they never married (but did remain best friends for the rest of their life and even after that). As to how much time travel was or would need to be involved to get her there, I honestly can't tell. Sumireko could be Renko's distant ancestor, but she could also be her sister or cousin, it's all fan theory and speculation as of now anyway. Though as far as my interpretation of Yukari is concerned, Renko would seem to be an unwanted entity in Gensokyo…