My success score was 9 at the start of the new system. It's still 9 now.
I did manage to increase the individual score of several of my gigs. But not yet high enough to put my success score at 10.
Sorry,
This is the harsh reality. Fiverr punishes you every time you receive a bad review. And if it is in combination with a bad private review, then it can take 3 to 6 months to recover from it.