1982? May or may not have been in the code, however, that said ...
... Fires cannot read code to see if they are allowed or not.
Yes, if that wall is the fire separation wall between the homes (referred as "townhouses" regardless of their size or price if there are more than two, if only two they are referred to as two-family dwellings, or ... gulp ... duplexes
).
That fire separation wall should be fire caulked along the roof sheathing and around all of the trusses, the roof sheathing should be protected for 4 feet out from the wall - measured from each side, there should not be any penetrations through that wall from dwelling to dwelling, that gypsum board should be 5/8" Type X.
Now, acknowledging that they are not going to replace the gypsum board nor install new gypsum board over it if not Type X, you should still them 'it should be 5/8" Type X for fire protection'. Your client needs to know and you need to tell them (to keep their lawyer at bay so he does not come a calling on you after a fire, especially being as this is "high end").
Normally, it is not too difficult to protect the underside of the roof sheathing with Type X gypsum board after-the-fact like in that case, however, being as they used 16d nails for roofing nails
- that's going to make it difficult to install the gypsum board up against the roof sheathing, so ...
... the easy solution is to now install the gypsum board on the underside of the top chords of the trusses.
Of course, though, I would also tell them that, when their neighbors unit burns down, the other half of the trusses (which are over their neighbors unit) are going to burn and their half of the trusses are not design to be 'free standing without support on the other side', i.e, there is a good chance of losing their unit due to a fire in the adjacent unit.
I might even humorously (and mean it, just say it that way) suggest that they put a smoke detector in their neighbors attic and wire it to their system, such that when a fire does occur 'over there' that *they* have time to react 'over here' and GET OUT!
While it is not much fun to watch your house burn down, it is even less 'fun' to watch that while you are *still in it*.