Ultimately, there is no way to exactly recreate the sound of a speaker cabinet in a room with FRFR. Just as you can't recreate the sound of a saxophone in a room, or a piano in a room or anything else. The speaker in cabinet is a resonating instrument in itself and should not be confused with speakers for sound reproduction: which is what FRFR does.
A sax has sound coming from the bell, sound from the keys, etc.: and it all mixes together in space. A guitar speaker cabinet has a resonance, and a speaker which is beaming a different frequency profile and phase relationship at various angles off the central axis and this all mixes together in space so that no location sounds exactly the same as any other: One step away sounds different, even to the extent that what one ear hears is subtly different from the other just by moving the head. This sense of subtle difference sounds "organic". An open backed cabinet and room reflections ups the ante. This is why engineers speak of a sweet spot for the mic: as every placement sounds different. And why IR mixes combining different mic placements might be preferred for a more general character profile. FRFR is designed to recreate sound that will be the same over a much wider field, and so has greater phase and time coherency in space. And a consistent sound field for an audience.
So, the choice is to use a cabinet and adjust amp models to work with the limited range that speaker allows. Which may be all one needs. Or use FRFR and have an infinite palette of speaker IRs to work with, which will open up a vastly greater range of amp tone options as well, but with a slightly different 3D experience. That said. I've been able to get very close to my actual speakers. A little reverb and enhance for in the room ambience from stereo output. Over the more than a year I've had the AX8: I've gone from preferring using a real cabinet to preferring FRFR in stereo for most situations.
