I've analysed the macOS 10.13 AMD kexts and FIREPRO W9100 uses Hawaii XT architecture [like the Radeon R9 290X]
Hawaii XT is referenced in AMD8000Controller.kext and AMDRadeonX4000.kext
Like
@tsialex suggests - it should work BUT it looks like no-one has ever really tested it/tried it.
Lou seems to have linked to a thread on the fully compatible WX9100 by accident.
Also W8100 can be ruled out - there is no Hawaii PRO GL kext support referenced anywhere in macOS..