posetcay: There seems to be a problem with alternative answer mode on this problem. F19-G18-A17 is not accepted as an answer when it is the second variation, but it works fine if it is the first variation. Might be worth looking into it.
kovarex: It doesn't look like a problem of the accepted variations. It looks like the T3 ending (as an alternative to T2) is just not considered in the SGF at all.
I will fix the SGF.
I'm afraid it might be somehow related to the problem, that when you add moves while failing the problem, the move is added to the tree and stay there even after reset, and these moves can also affect the right/wrong state of the branches and show in the tree?
I'm planning to make a change, that moves outside the tree that you added during review and solving would still be in the tree, but specifically marked in the engine and shown with a different coller in the tree and with the dots (blue?).
Then, when you hit reset, these moves would be removed from the tree, and these moves would be also ignored when deciding the correct/incorrect state of the branches
So I added the alternative move to the SGF.