Harmonic balancer 101
 

A few weeks ago I replaced my entire drive belt system.
Idler pulleys, tensioner, the works. 2003 M62 4.6.

After completing everything, I noticed that my harmonic balancer is not
perfectly true. Perhaps I watch to many Jet engines that are balanced to the nearest nano gram. I thought the balancer should rotate perfectly.
I have zero belt problems or any vibrations.
Am I overthinking this?

If you're not getting any vibrations or odd sounds then you should be fine. Though for what it's worth it's not super hard to remove/replace the harmonic balancer— you just remove the belts and undo 8 bolts on the harmonic balancer and it comes right off. You don't have to touch the big crank bolt at all.

The trouble is finding a replacement— most will be the same given the age and mileage of these cars. A new one is around $500.

If it's not causing any problems then just leave it as it is.

I have a good spare if needed