Finnair Plus - AY reward booking classes

A number of years ago I remember upgrading a couple of my LHR-HEL-LHR trips to J on AY. Back then I called up the service centre and asked them to confirm whether there was availability in booking class R. Based on some of the recent threads I've read here, R is now something completely different. I've recently acquired a heap of AY points and am planning on using them for upgrades again, so I was wondering if anyone might know what the new booking class is for J rewards.

Class is F.

R is cheapest Y class you can get (not in Finland).

Class is F.

R is cheapest Y class you can get (not in Finland).

That's exactly what I needed to know - thanks very much!