Since a core mechanic of the game is also lynching, and it also deterred, the balance or "lack there of" because Jester can win because of these fundamentals, isn't the role's fault. What it comes down to, is who plays better, determines who is punished. I've stated time and time again, Jester rewards whoever plays better. Scum is more susceptible to this, but don't forget, they can
also manipulate town's weapon: lynches.
All in all, Jester can win easily, but the consequences should deter this. Assuming they don't, it's a 3rd Party Benign role that doesn't care who wins, and can work with anybody. It's an individual goal, not a team effort, so Jester winning with ease isn't much of an issue.
Perhaps rewarding little, to no ELO for Jester wins would be applicable? I honestly believe this variation of the role would act as an essential balancing tool. So claiming it's too easy to win with, and therefore "bad", is moot.
TL;DR:
This role is balanced, the issues being pointed out can be attributed to the game. Which really, if you look into it deeper, aren't really issues.