Almost all, but not everything, can be done with the Flexbody, as long you respect the image circle of a specific lens, use that lens at F16 and how far/close you are from your subject. Even the scheimpflug movements can be done, then the baseline has to be tilted. Anyway, the level bulb (niveau à bulle, I don't know the correct English term) is very important and in some situations it should be in perfect level.
When the back is out of level, then the subject wil show oblique deformations or the scheimpflug sharpens will be not that good because here the sharpness is done by the lens mouvement, see, as an example, the picture I made with the S-Planar 120 mm, in attachment, this is set for table top.
See the manual too, the Flexbody is a fine tool...
BTW, trial and error might be your best teacher...