So, I'm assuming that the "(or half the bonus for one-way travel)" part implies that one gets have the bonus if it's round trip travel, but only one way is in a qualifying class? We have a flight where one direction is a non-qualifying economy fare, but I up-fared to "I" on the return in order to do a flight change and get SWU availability (J->F in this case). So, we should get 12,500 for this trip, yes?
Cheers.
I have a one data point (anecdotal experience) from a year ago or more, not quite similar.
There was a similar offer. I had a Premium Economy (outbound) and Economy (inbound) ticket.
I got the FULL bonus not half and miles posted before I had completed the return portion. I guess the first segment triggered the bonus.
But...who knows what will happen this time. Systems may have got smarter.