I've managed to complete all three Solstice set glows, and got the Partially Resplendent triumph complete, but no progress is going towards the Cosmically Resplendent triumph. Is that intentional? Neither says anything about completing them during Solstice. Bungie said we could complete the glows after Solstice had concluded, and I took that to mean the triumphs associated with them could be completed too. That appears to be the case with Partially Resplendent, but not Cosmically Resplendent.