A dark planet with an even darker history, Malachor is a location Jedi are told from a young age to avoid. Home to an ancient Sith temple, it was once the location of a heated battle between Jedi and Sith. Kanan, Ahsoka and Ezra traveled to Malachor in search of knowledge, but were met by evil.-Databanks
When Vader focused her down she was bulldozed off of a cliff, your point?
Nyriss being an evidently very high tier duelist, should easily be capable of keeping up with Tahmoh and her physical augmentation is obviously on a level that Tano has a very hard fight.
The Force disparity is clear and it can end Tano fairly quickly, it doesn't even need to be charged, one hit and suddenly Tano is in a Force exchange she cannot win.
Sabers: we don't really have an established upper limit for Nyriss here, but her an slaughtering of an "expert swordsman" like Scourge and an even better swordsman in Meetra, and especially being so fast, ferocious, and skilled that she could instantly put both of them on the defensive despite jumping in between them, is enough evidence for me to believe that this is at least a stalemate.
Force: shouldn't be too much debate here tbh, Nyriss has a level of versatility that Vader doesn't that would confound Ahsoka, most notably Nyriss's immensely powerful force lightning, though given Nyriss specializes as a sorcerer, that isn't out of the realm of imagination for her either.
All-Out: Ahsoka certainly matches up with Nyriss as a swordsman, but if anything, Nyriss's incredible force powers win her the day.