As for me -- you can always ask for permission from both the author for using the files/setup taken directly from them. I mean, since you already said that you have it from. Granted, it's not impossible for someone happened to create similarity to what others did, and for that I believe it's fine to release one [without direct permission] -- at least on modding practice, far as my concern. And that's from etiquette perspective. What makes them legit or not from what I see is whether they can provide support to their work. If they can, then it's good -- if not then they better don't.
As from practical perspective I guess it'd be better if you create something that at least at the same level -- both in compatibility as well as quality -- as what it means here at least you don't make new problems that didn't occur previously.
Lastly, consider releasing this or any of your mods using TSLPatcher as possible -- regardless of how difficult for you to pull that one off, you'll find it more rewarding than the other way around. Cheers, and good luck! 🍻