There was - I'm glad someone read it!
In typically ambiguous Japanese fashion, R can mean anything from a panel being taken off to repair a pin dent to the whole front end of the car being wiped off the map by a bullet train. It's a fairly simple process - the inspectors check the bolts holding the panels on (at the front end) to see if the paint is cracked (indicating they've been removed) or the welds on the rear to see if they're factory welds or paint shop ones.
As a general rule, a 0 or R grade car shouldn't be an issue for compliance if it only has a single panel replaced. If there are two adjoining panels replaced (like the bonnet and one of the front guards) chances are the structure of the vehicle has been repaired, and this should be a no-no for compliance. With 0 or R grade cars, inspection in the metal is a no-brainer before purchasing.