We need new artists it appears, I'm traveling a lot because of work, but I will try to get on and make a a list of what's needed for New textures, and some updated textures. I'm a bad artist so there's not much I can do but update the classic and transparent GUIs and the pack zips. Hopefully we can get some more people who would be willing to contribute to the pack.
So I have created an updated list of missing textures for 1.12/1.13. I cant update the OP at this time because the account it is made with, I cant currently access, but hopefully, il be able to fix that soon. I'm going to work on updating the Classic/transparent UIs for 1.12/1.13.