Hello, I installed this mod and am very pleased with the way windows connect with it. I cannot seem to get anything else to connect though. Borders between sand and grass are still square, as well as other blocks. I do have both the resource pack and the window culling enabled through the resource pack setting. Any help would be appreciated, thank you

The builtin pack only changes glass.

You need other resource packs for other stuff.

What are they called?

What are they called?

I can't tell you as there are several. You find them on resource pack sites. Most of them will list connected textures, ctm or Continuity/Optifine support.

That's what you need to look for.
Note: Just that it mentions it doesn't guarantee that it actually does support it.