I'm pretty sure this is well known, but I decided to ask.

Schist seems to have some weird orientation rather than sticking to a fixed top and side. So sometimes the top texture is on the side, and even the orientation of the pattern itself seems to change on a few block, so even if the top texture is the same across, in some blocks it goes in a way, and other blocks in another.

This doesn't look very nice to me because there do not seem to be rules or patterns that make it look consistent.

But again, was this by choice?

This was intentional, since only having one direction is boring
You can change this with a datapack.

Since this issue wasn't closed and without opening another pointless one...

Is 1.19 planned? I'd have no problem staying on 1.18 but I'm trying to make a modpack and most of other fabric modders have already moved on and dropped support for 1.18

There's still stuff lagging behind like tinkers, create and botania so it's not a big deal. But at least Create should come out sooner than later. Having a mod that deals with worldgen up to date would help a bit.