As I was the starter of this thread I might post back on what hapened.

Yes, as predicted yesterday's AY69 was completeley full in C, probably due to the fair season. So the upgrade request was denied. My vouchers have already been re-credited to my account, so that is all well and exactly as told above in this thread.
2 other pieces of information that might be interesting:

1. The checkin operator said that due to my platina status, my upgrade request was prioritized and that no one else was ahead of me. This was also true even if the request was not for myself but for a family member travelling with me. He also said that there was a long waitlist. I obviously don't know who else was on the list but FF-status do seem to have some effect in how upgrades are processed.

2. My partner was given priority tags on her luggage, and it also seems like the seat next to her was blocked. This can just be a coincidence, but I wonder if AY have started to block seat next to elites if space allows? (At checkin at NRT 3 weeks ago I was specifically told "the seat next to you will be empty on this flight, enjoy!") I have not experienced this with AY before. The plane was very full in Y aswell, and she had empty seat on both legs so I am leaning towards a undocumented perc of platina status.