After reading that the European Sylvania Relumina ceramic metal halide retrofit lamps for the European market utilize a built-in inductor to help achieve significant energy savings by adding a series impedance between the mercury vapor reactor ballast and the arc tube, I also understand that reactor ballasts are often highly sensitive to variations in line voltage and AC frequency. Generally, a higher applied line voltage means the lamp draws more current while a higher applied AC frequency means that the lamp draws less current.

Ideally, I am pretty sure that these lamps in particular are generally optimized to run on European 220-240V 50Hz mercury vapor reactor ballasts.

If I was to operate the 85W or 80W Relumina retrofit lamp designed for 125W mercury vapor ballasts on a 220V 60Hz mercury vapor reactor ballast designed for 125W mercury vapor lamps, would the higher AC frequency cause the lamp to be underdriven compared to operating it on a 240V 50Hz 125W mercury vapor reactor ballast under the assumption that the ballasts are operating on the correct voltage and frequency?

Internal choke will have 20% higher impedance than intended, sure. I'd say the lamp will run underdriven about 10% by current on your ballast.  Hard to calculate exactly due to multiple nuances, easier to try a test run and measure the current.