You could take the texture and try using https://remove.bg to remove the backgrounds, then make the color of the part the color of the texture, assuming the transparency is causing the black
I’ve just tested this texture in studio, and I get no black lines. But, it might be because of the tiling you have on, so what is your StudsPerTile on this?
Nevermind, i found the actual problem. its because the side texture is sticking to another block side texture. Now i just need to code a system to update it everytime someone place or break blocks