If easement does not exist, and access road not owned, then its not just an FHA issue, its a lending issue period. No lender will take that on. Definitely let client know.
Not our job to do courthouse research on easements/survey type issues. If lender won't supply that, then state what info you have and let them decide.
Some states will not allow a dwelling to be land-locked, but each jurisdiction is different.
I have seen 'shared' driveways, both with and without recorded easements. Sort of like an HOA that owns the sliver of land the road is on. Have also seen one person own the entire access road to subject's driveway, with an easement allowing use. Again, those can be recorded or not as well. Really fun when they are not recorded. Or there could be no easement at all. Real fun those are.
These can all be a cloud on title.