Thanks to everyone for their ideas and feedback on this. The situation has been rectified and was fairly simple. It really comes down to two factors.
The first is that there were no parking brake parts on the right side (shoes, springs, activator, spacer bar), which was a surprise. I had a new set of unopened shoes on hand from last year. I was lucky enough to find the small parts from the Volvo part recycling shop on Vancouver Island. That took care of the missing parts.
The other issue is the cable geometry. I know from the PPS parts that I bought for the project last summer that the inner cable is about 20 mm too long relative to the length of the housing. The repair shop had identified this with the first set of cables they tried but failed to come up with a working solution that they were happy with. They added extra spacers under the nut that terminates the inner at the lever. While this is somewhat correct, it is not very elegant for a couple reasons. I elected to add the necessary spacers between the housing end and the lever body termination. There were a few other clean-up items from what looked like a rushed job that never got to the tidy-up phase.
I now feel confident in parking the car and having it still be there when I return.