Unpopular opinion but I wouldn't automatically accuse the ground agent of lying regarding how the downgraded pax were selection - I'd go for ignorance first and foremost. Does it help? No.
Also asking ground staff to somehow ensure inflight service (ie J wine or F&B in Y) - while I understand the point - seems a bit of a stretch imo. That is up to CSMs (as you luckily found out whuch was great effort by that CSM to make right as best they could which is a real credit).
Also all the seat shuffles suggested.. QF had already disrupted two pax.. they wouldn't want to be shifting around more pax in rows 4 and 5 imo. I mean imagine the AFF thread "Selected row 4 and moved back without notice for a couple to sit together" - I mean then you potentially piss off more people.
I have no problem with asking the question but I can see the push back.
I'm sorry your, or part of your anniversary trip was messed up by this. So coughpy
at least the CSM really came through.
Hopefully the rest of the trip is kuch better and happy anniversary!