Add code of CTM mod into models will cause model error in 1.15.2. And CTM mod doesn't support 1.15. Optifine CTM can do the same thing but need a little work.
This is an example of Optifine CTM, affects fiery block.
(This resource pack cannot use directly, but it can be placed in other packs)
CTM_Fiery_Block.zip

No

CTM mod doesn't support 1.15

False, there has been test builds already.

Not to mention @Drullkus, one of our devs, is also a dev for ctm (and chisel for that matter).

Also, the more important factor is that Twilight Forest for Minecraft 1.15.2 is not even qualified for alpha testing stage. There are even missing blocks. The dimension is totally broken.
The current focus of the dev team, AFAIK, is to get all blocks/items/entities fixed first, then take care of the world gen rewrite from ground up. Mod compat is very very low priority to my knowledge.

Haven't you considered that both mods are being worked on. It's not complete.

Also, the more important factor is that Twilight Forest for Minecraft 1.15.2 is not even qualified for alpha testing stage. There are even missing blocks. The dimension is totally broken.
The current focus of the dev team, AFAIK, is to get all blocks/items/entities fixed first, then take care of the world gen rewrite from ground up. Mod compat is very very low priority to my knowledge.

But using CTM code in model files will cause MODEL ERROR (full block with black and purple texture) if CTM is not installed, and after only deleting CTM codes, models will work correctly

Twilight Forest will use the CTMod, there will be no change of position on this topic.