OS 9 ran on PowerPC CPUs (like the one in the Wii) and more or less supported ATI and NVIDIA GPUs of the era (90s), but the GPU in the Wii, which can be traced back to the GPU in the GameCube, was created in 2000, so I would guess it’s a small change between the ATI GPUs of the 90s and whatever they changed for the GameCube GPU, which then was passed down to the Wii GPU.
Graphics drivers are always a fickle thing with modern hackintoshes, so I would guess it has to do with the GPU “driver”. It could also be related to VRAM as the GameCube and Wii GPUs were likely both significantly weaker than the average desktop GPU of their respective eras. I know for sure the Wii GPU was already antique when the Wii was released because the Wii only output up to 480p, a joke in 2006 when 1080p TV were starting to become mainstream… so from that perspective we can’t be surprised that this thing is struggling with text rendering, if the GPU is indeed the culprit.
HW accelerated rendering was supported at least as far back as System 6.0 in 1990
Classic MacOS used an API called Quickdraw, which was implemented as a series of graphics primitives (originally written for the Lisa as part of LisaGraf). Quickdraw implemented support for things like drawing lines, rectangles, etc. The original implementation software rendered them onto the system frame buffer.
Essentially all drawing went through Quickdraw, which made it a natural chokepoint to introduce acceleration, which is exactly what happened when Apple shipped the Macintosh Display Card 8*24GC in 1990. The card included a separate Am29000 processor (which was often higher performance than the host CPU), which had its own memory and an implementation of Quickdraw. Its driver patched the Quickdraw calls in the OS to RPC them over the bus to the card, which would then render them on behalf of the host. It also supported off screen rendering and DMAing the results back to other cards.
You could argue that is still software rendering, just on another CPU, but at the end of the day that is sort of orthogonal, almost all GPUs have some programmable components you need to load firmware into in order to operate. The key point is that there was an abstract interface the OS could use to offload rendering to some other device besides the main application processor, and the UI used it.
I honestly can't recall how much of this was still in common use by the time Mac OS 9 came around. CPUs were also much faster by then, and the move to PCI meant it was possible to use fast off the shelf PCI GPUs which may have changed the cost benefit ratios enough that it was best to just take whatever the GPU vendors were offering and software render into their frame buffers even if it could not fully accelerate all the same operations a bespoke earlier design could.
Graphics drivers are always a fickle thing with modern hackintoshes, so I would guess it has to do with the GPU “driver”. It could also be related to VRAM as the GameCube and Wii GPUs were likely both significantly weaker than the average desktop GPU of their respective eras. I know for sure the Wii GPU was already antique when the Wii was released because the Wii only output up to 480p, a joke in 2006 when 1080p TV were starting to become mainstream… so from that perspective we can’t be surprised that this thing is struggling with text rendering, if the GPU is indeed the culprit.