In the WikiPedia link that popped up in your post, it sure sounds like the Card was supported through the IIfx period.
That said, the Mac IIfx had very funky I/O subsystems utilizing Apple II Procs (6502s?) to speed throughput. From the sound of the Mac286's use of Mac II I/O ports such as both the modem and printer ports as PC Serial Ports and the Superdrive as an IBM 1.44 FDD, my best guess is that its drivers die a brutal and ugly death when faced with the Mac IIfx Architecture.
That said, the Mac IIfx had very funky I/O subsystems utilizing Apple II Procs (6502s?) to speed throughput. From the sound of the Mac286's use of Mac II I/O ports such as both the modem and printer ports as PC Serial Ports and the Superdrive as an IBM 1.44 FDD, my best guess is that its drivers die a brutal and ugly death when faced with the Mac IIfx Architecture.