Originally Posted by nightwalker
If it doesn't restore by the respective backup tool you backed up from, and as you are telling that it needs G+ to backup so possibly there aren’t ways recovering your old data.
All I can suggest you now is start from the beggining and keep the G+ backup incase anything wrong happens or you need to change ROM.
Nicely I have a backup in the firmware by TWRP, I can just login G-games on firmware to take out my old account.
Btw a new game account is now present before awaken to the above backup by TWRP.
Also I have an One V recovering the data from G-games in 1 of my 2 MOS accounts, I can thus be in a MOS co-op with myself.