The mod assumes that the block is 6-sided, but is difficult to do anything with 4-sided facing blocks. There, should be a better way to make blocks connect diffrently depending on where they're facing

Why would you not be able to do that? You can make textures connect to specific blockstates, and you can even have a different models for the block itself based on its own blockstate using a vanilla blockstate file.

I read about having different connected textures for different texture sides, but I didn't see anything about per blockstate connected texture

In that image both of the bottom right blocks use the same texture from the texture map

different connected textures for different texture sides

What is this even supposed to mean? I am still not too sure what exactly you are trying to do.
If you just want the texture to connect to specific block states, then you should just use a match_state connection predicate.

I didn't see anything about per blockstate connected texture

You can use a different model per blockstate. That is a vanilla feature, that is what the blockstate file is for.

different connected textures for different texture sides

What is this even supposed to mean? I am still not too sure what exactly you are trying to do. If you just want the texture to connect to specific block states, then you should just use a match_state connection predicate.

I didn't see anything about per blockstate connected texture

You can use a different model per blockstate. That is a vanilla feature, that is what the blockstate file is for.

The blockstate, doesn't help. I am trying to make the connected texture follow the 'path' outputs. In the first image I showed where I want them to connect, in the second I show the direction they are connecting to. Both blocks on the bottom right use the same texture, so I cant make it a ↗ texture, because that, will mess up the other one

This is very unclear, I have no clue what you mean.
Is there something specific you are trying to do and can't?

There isn't a way for the mod to distinguish between

and how the textures should be connected(lines show where to connect)

Why would you not be able to do that? You can make textures connect to specific blockstates, and you can even have a different models for the block itself based on its own blockstate using a vanilla blockstate file.