It depends on the definition you want to use for "tempering", but at the very least I would say that the Echo qualifies as being tempered by Hydaelyn. I imagine that if the Twelve are what they are believed to be, they would also be capable of it. Elder primals, for that matter, are likely capable but in far less need of doing so, since their shared commonality appears to be "is already summoned and cannot be permanently removed from the world", and they would therefore have far less use for faithful servants to summon them.
