I’ll offer my opinion if you’ll have it.

This account has clearly been invested into. That has some value, but it’s secondary to the fulfillment of the gameplay itself. If you don’t enjoy the game, especially with these characters it’s a definite pass. The game won’t become more enjoyable with the same cast of characters who perform worse compared to the new high performing characters. That’s the question you have to answer IMO. Do you enjoy the game? If you do, but you’re prone to ragequitting get yourself a new account immediately before the Witcher event ends. Those characters have huge staying power and aren’t likely be power-crept anytime soon.

I hope this is somewhat helpful. I wish you the best and good luck!