If the chain line is happy, then I wouldn't worry about the drive side. The purpose of the shims is to allow the wavy washer to apply a bit of side-load the bearings. Without them, the spindle would rattle sideways between the bearings. This is different from the Shimano and old style Gossamer cranks that use a crank bolt to apply that load, and pinch bolts to secure the crank bolts. If you want, try reattaching the left crank without the shims and see if the spindle doesn't slide sideways.

Here's the link to a diagram of the Gossamer double crankset. https://shop.fullspeedahead.com/en/f...b38c24796a658/

And FSA cranksets are not junk. Truvative and SRAM have used a similar system with their GXP cranks for years.