That said, Windows has highly configurable font hinting/rendering so I'm perplexed as to why this project is a thing
It's still possible to force (most of) it to the good old MS Sans Serif and with no antialiasing, the way I like it, but it's getting harder with each new version.
I have a feeling that this exact idea is the reason why most Linux DEs look like crap [to me]. The way fonts look (especially those used in the system UI) is, just like colors or margins, [in my opinion] a matter of design, not just personal preference.
blender is a notable exception, though.
See Krita for another OSS project with great UX.
And this is what my yearly-or-so foray into Windows shows up - most apps look like garbage. The handling of displays with different DPIs connected to one machine is even worse. This has even been a solved problem _on Linux_ for quite some time.
This is big problem on Windows, where the heavy-handed hinting means actual font size doesn't even come close to being linearly related to requested font size. So you can't even make the simple assumptions such as that the same UI layout will work if you render everything at 2x for a high DPI screen.
Third-party apps, on the other hand, do seem rife with clipped text, even in English at nonstandard DPIs.
Edit: Ah, this was already said by the existing sibling comment.
Chinese/Korean rendered incorrectly on English UI because system hardcoded a font fallback, which put Japanese font first, regardless of how languages are ordered in the Settings. This is largely true for traditional Win32 programmes, like Chrome, Edge, Explorer.exe, etc. However UWP apps using the new UI framework (like Unigram, Intel Command Centre etc) behave correctly if setting Chinese/Korean as secondary language.
It's different on macOS or iOS however, if you set a system locale order as 1. English, 2. Chinese, then Chinese content will render correctly with correct Chinese system font PingFang.
Another issue that is also very important is that Chinese (Simplified or Traditional), Korean and Japanese share amount of the same characters but written differently. That means system must render the glyph in correct variant, like in the example of Source Han Sans
https://github.com/adobe-fonts/source-han-sans/raw/release/S...
How much you can, or can't modify as an end-user probably relates to the HIG and general usability and transferability as well.
In some ways, there have been cases where you cannot change the background of things, or at least not in an obvious way. I suppose it really depends on the specific user and their user-case to have that matter (or not matter at all).
Within UX you can focus on many things, be it an abundance of choice vs. known defaults, aesthetic vs. utilitarianism, CAPEX vs. OPEX etc.
Edit: for those who don't believe me for whatever reason, https://www.howtoguides.org/change-your-desktop-background-i...
What if I want my taskbar in the middle of the screen instead of the top or bottom?
What if I want textboxes to have flashing orange outlines around them?
What if I want the close button to be blue instead of red?
What if I want the Finder face to be a sad face instead of a smile?
Customizability needs to end at some point. Technical details about font rendering is not important to 99+% of users and is only confusing.