There are only 2 authentic Nuscho’os:- Ashkenaz!!! & Sephardi!!!
Sefard is so jumbled with so many different versions, because it is far too young/recent and with no basis, 300 years being very recent compared to Ashkenaz & Sephardi having been around for well over a millennium.
It is no accident that most Yeshivas & Young Israel Shuls Daven Nusach Ashkenaz, as it is so exceedingly authentic.