Personally, I wouldn't redo it. Let sleeping dogs lie. Yes, you understated the liability, but they contributed a sufficient amount to cover it either way. If someone asks you to redo it in the future, then redo it then.
The beauty of the PPA funding method is everything self-corrects over time. I would suggest that you don't apply any of the excess contribution to the PFB. That way the plan is right where it should be starting in 2023 and no one can argue that your error impacted anything. Plan was appropriately funded, PFB was not impacted, no harm, no foul.
I applaud your dedication to making sure the valuation is correct, but in reality, you are probably the only one who cares. Or, go ahead and redo the val and amend the SB if it helps you sleep better.