Yeah, I wonder if we should have found an excuse to drop some other golden icons. At one point I'd planned a book that compiled ziggurat dungeons for all the planes, but by the time I was supposed to work on it, I mostly just wanted to wrap up the main plot, not add more side quests.
So, where to add more icons? Avilona and Urim in adventure 1, Apet in 3?
So we could have put a Nem icon in the Crypta Hereticarum in 4.
Maybe Rock Rackus is wearing a Jiese icon as jewelry in 5.
In 6, perhaps some Beran archaeologist is giving a private lesson to Cavallo de Guerra's kids, and he has an icon of Mavisha, recovered from the archaeological dig the PCs visited by ship in 3.
In 7, well, the Ob could have several newly made ones that aren't quite up to snuff because they're intended to only last for the few days of the convocation.
During 8, the group gets the Lost Arc of Reida. I'd probably have a 'past' copy of the golden icon of Reida be in Nicodemus's possession during one of the memory events, where he's showing off a discovery to Kasvarina as part of an argument that there is an ideal moment - around the year 500 - when it'll be easiest to alter the Axis Seal ritual. The PCs would have to wrest the icon from him and then will it into existence when the memory event collapses.
Then the golden icon of Av should be in Thistle Palace in 9, a gift from some previous monarch of Risur.
Importantly, there's more than one icon for any given plane, and they're not that hard to make, so the Ob would clearly have spares.