The balance and noise problem is a lot more of a challenge when you consider
dynamic balance
You can start out with something as simple as "knife edge" balance where you place the fan shaft on a frictionless knife edge and watch which blade goes to the bottom. Only to find that it still shakes the bejeebers in a dynamic balance machine.
Then you find out that you have opposing equal masses but a foot apart or more in the axial direction. For that common occurrence in gas turbine rotors you need a means to balance out these forces with two balance planes after the fancy balance machine tells you where to put the weights. Thus the designer needs to add these balance planes to the rotor design (having a balance ring with rivet holes for these weights is common).
I think that race car drivers are faced with similar challenges on the engines as well as the wheels.
Then for fan engines with those fancy looking twists you find that the mass is never uniformly centered along a constant radial line so just a change in twist in a single blade can affect the imbalance felt. Thus you can have4e a bird strike and not even lose any metal but yet the fan will sing out that it's vibrating like hell.
I've heard of mechanics spending days across multiple flights trying to on-wing cure a fan vibration problem with balance weights when it ultimately turned out that one blade had untwisted slightly after a bird strike the week before. One can imagine how difficult it is to see an abnormal twist in one of these scimitar looking blades by looking in an inlet