So uhhh... I'm not sure where you got the idea that there was no CTM support for these...

Just put this on top of continuity's CTM, and boom, basic slab CTM.

glass_slab.properties

matchBlocks=mo_glass:glass_slab:type=bottom,top
tiles=0-46
connect=block
faces=top, bottom
resourceCondition=textures/block/glass.png

There's a little bit of jank with double slabs, but CTM does work with both slabs and stairs. If you don't believe me, I will make a PR to prove it.
Stairs will require many, many properties files...

Great to hear! Yes, a PR for this would be very welcome. 👍

(Even if it's just a proof of concept for the normal slabs and stairs. I can write a script to generate the remaining config files from there.)

Alright, I'll get started on it. I will submit a PR adding an built-in resource pack that will enable it.
It's going to take a bit to get CTM working correctly on the stairs, because I need to get the orientations to connect right.