Jasmine I don’t think was supposed to be evil per se. She was was a power that be that was sick of siting on the sidelines watching humanity devour itself. So she became involved. Some have said with Buffy fighting the first evil that year Angel was fighting the first good.
Actually back in the day someone wrote a good fan fic conversation that Jasmine and the first had as their plans were coming to fruition at the same time. I believe that author insinuated that Jasmine knew what the first had planning/up to since Season 3 of Buffy and this was her counter plan to save us. Hence the powers making it snow in Sunnydale at just the right time.
Jasmine’s argument is interesting “I eat 40 people a day but prevent thousands of killings in war”.
It’s hard for me to call it a “Good” so much as peace by absolute control, like the extreme law end of the law/chaos spectrum you see with the Vorlons, the Mass Effect control ending, etc.
I liked the mini-crossover when the First appeared to Connor as Darla.