There is an interesting article here,
https://www.altairastro.com/ed-glass...formance..html
Comparing glass types and optical performance. It seems to peg the FCD100 Abbe number a little below FPL-53, but its much better than FPL-51.
As always the element it is partnered with, doublet or triplet design, etc all play a role in final performance. What can be acceptable visually may not be acceptable for imaging. Much of the discussion of the new crop of 150mm ED refractors on CN, is being led by guys that want it for visual use. It's going to be very hard to convince imagers that anything less than an equivalent of a FPL-53 triplet is going to be good enough for serious imaging.
I would find claims of FCD100 superiority to Flourite Abbe number to be pretty far fetched without diagrams to support that design.