You've poked a bit of a sore spot with me on that, even though I know it wasn't your intention.
I know the guy who puts those patchers together. He's a genuinely good guy, incredibly intelligent, and he's done some crazy circuit level repairs and CPU swaps for me. With that said, he's bowed out of the patcher game from my conversations with him.
C2D machines could function fairly well up to about macOS 10.13. I say this from first hand experience with running several patched machines.
At 10.14, Apple started requiring a new GPU instruction set called Metal. When this became a requirement, it rolled a whole lot of systems-basically anything introduced before 2012-off support. The 10.14 and 10.15 patchers largely function with no graphics acceleration, or limited acceleration that's kind of pieced together from drivers, and are miserable to use. Aside from that, there are a lot of hardware incompatibilities that crop up in specific systems.
I am a member of a Facebook group where nearly everyone installs those patches on their C2D systems that can run newer OSs, and it's an endless stream of problems and things just not working correctly or updates completely killing the install. I've seen people foolish enough(and I know that's a harsh word, but it's how I feel about it) send customers from their shop home with OS-patched computers and have inexplicable problems, or even worse people deploy it on mission-critical computers and get caught when something breaks.
There are folks who make a hobby of making unsupported OSs work. I don't have the smarts to actually do it, but I have a friend who's managed some amazing stuff at it. He doesn't have a lot of real hardware to test on, so in the past I've run-and actually had fun with in a perverse way-patches that he's put together. One of my favorites was running OS X 10.4 on a stock Power Macintosh 8600/200-a miserably slow experience that was more proof of concept than anything, but still really interesting. It's something that has its place, but IMO not in a primary computer.