"polygon stretching" ? You mean that some triangles are morphing? In Minecraft 1.7.10 one of the triangles morph when you get really close to the block's side.
Yes I meant vertex explosions XD. I couldn't remember what it was called so I tried to describe it lol. And yea, Cemu was pretty much made for Nvidia users only. They didn't do too much for other brand users until version 1.16 (with the Vulkan backend being added)