If by rp you mean resource pack, then it's both yes and no.

If the resource pack is made for a project (map, server etc.), then you can use my models in it with credit. That way you can publish it without problems.

If it's for your personal use and will be seen and used by, let's say, friends, then it's okay.

If there isn't much of things that you've made yourself for the rp (for an example, if you're just making a compilation of packs) and you're planning on publishing it, then it's a no.

If I couldn't answer your question, then, please, just give me more info.

It works for the newest versions as long as the optifine for them is complete, when I update a pack I basically do nothing but change one line that only prevents you from getting the "wrong version warning" message (this warning can be ignored, since how been said I don't really change anything when I update packs). I can update my packs, but it's just a waste of time, since everything already works.

If it doesn't work on 1.18.1, then you probably doing something wrong and I can't help with it.