Datapoint: Booking that I flew a couple weeks ago, outbound segment 1 (AC) credited correct SQM and SQD, but outbound segment 2 (UA) credited the correct SQM but lower-than-expected SQD.
The SQD for both segments doesn't seem to add up to the base fare for outbound or as seen in the cowtool... Must be something wrong with the way *A partners are crediting SQD to Aeroplan.