Ah, that version is for old, old versions of Minecraft: the Alpha versions. It's specifically designed for Alpha 1.2.6 but should work with earlier versions. It's just the current textures made into the old-style texture pack formats that the old versions used.
Not that version (it only has a few textures because Alpha only had a few blocks), but yurisuika is keeping the full version of Isabella II updated over here. You can track the development on the SuikaCraft Discord.
Original artist bonemouse gave us permission to mess with it:
Anyone wishing to continue my work has my permission to do so.
yurisuika has been perfectly happy with me messing around with my own variants, so I'm pretty sure it isn't going to be a problem. To be safe, leave a readme in the resource pack folder explaining where it came from (bonemouse and yurisuika, with a link to this thread or suika's github), and change the name of the pack to something like Isabella II - [map name] version
Well, I'm going to say now, that after doing a bit of messing around with it, I've deducted that while I can fix the gold textures to be colored like gold, I'm nowhere near good enough to fix a lot of the faces.
It's a good texture pack, but I don't like the blazes, the faces (especially the villagers, ew), the witches forgot their hats, the classic blunder of having the wrong color for gold, and a few more things. Like it said, it is a good pack, but not one that I can tolerate.