In my experience, PF jars can look uncolonized in a corner, but actually be 99%. I think the bottom corners sometimes do get gas-locked or dry out and there can be a little patch on the outside, against the glass, that just takes forever to finish. I decided not to do cakes and wanted to spawn the pf jars to a monotub instead. I waited as long as I could then spawned them all at the same time with some still showing those uncolonized patches. But when I slid them out of the jars, I realized it was just the outside grains which I brushed off a bit before simply crumbling the cake into the bulk substrate.
I wouldn't try to add more GE at this stage. Some jars take longer than 2 weeks, give it another week and see how it progresses. By then it should be pretty much done, I wouldn't worry about the corner patches like I said, and you could probably birth it with a casing or spawn it. Or if it still has a big uncolonized area then that's a little more suspicious, could be stalling to a hidden contamination.