What you need here is [Person:Poss] which means "person possessive". As you have already found out, having the apostrophe s hard coded in the template can have undesirable consequences. [Person:Poss] may rotate between John Smith's and his. To prevent the rotation, you can say [Person:Full:Poss] for the possessive form of the full name or [Person:HisHer:Poss] for the possessive form of the pronoun. The pronoun qualifier also supports :HeShe and :HimHer as meets the syntactical needs of the sentence. The pronoun qualifier obviously is rendered based on the gender of the person.
It would be much better for RM to delay the release until after Legacy 10,
I would go even further in the opposite direction. I think it's so important to get RM8 out the door that it should be shipped with fewer than planned new features if that would get it out the door faster. Of course it shouldn't be shipped until it's been well tested and it shouldn't be shipped with no new features. But from a user's perspective, essentially all RM progress is at a standstill until RM8 ships.
Which source template are you using where the source details fields have been omitted? In particular, is it one of the built-in ones, or is it one of your own design?
In any case, if you know which Master Source is involved, you may be able to find the places where the data is missing by using Lists>Source List and then Print for that Master Source. Be sure to turn on all the check boxes before you run the report. You will pretty much have to scan the report by eyeball, and it might be helpful to save the report to a file to assist your your scanning.