I think they are counting 4x5s and all the variants of the aptus mounts, you can’t change between them sadly.
Yes, apparently there was an internal contest with the Leaf marketing team for who could come up with the highest nonsensical number of compatible cameras for the Leaf Digital Backs. Somebody won.
Generally speaking, modern digital backs (since around 2010 - ish and since) have dedicated, fixed specific camera mounts that are not removable/exchangeable, typically in one of four primary mounts:
Hasselblad V
Hasselblad H
Contax 645
Phase One/Mamiya 645
Due to flange distance tolerances, any digital back in one of the above interfaces cannot be adapted to any of the other interfaces. Some of these digital backs, via various adapters could be coupled with Mamiya RZ, Mamiya RB, Bronica ETRS, Fuji GX680, due to the deeper bodies. The optimum value of these latter pairings is not straightforward in all cases.
These digital backs can fit on any view camera or tech camera whose manufacturer produces a compatible interface adapter based on one of those four interfaces. Current examples being - Arca Swiss, Cambo, Alpa, going back a bit further, Sinar, Horseman, Rollei, Toyo, etc.
Steve Hendrix/CI