Okay, chill out and take a breath. You haven't "broken" your corgi boys.
You didn't have any frequent limping when they were younger did you? Pano is like growing pains and exhibits in random limping. They are at good weights and coats are healthy right? They're going to be okay. Remember, I was the one who did say there was
no universal consensus on feeding or when to switch. IF the boys like the puppy version of whatever brand you are feeding, then get a small bag of the adult and begin switching them over now - isn't going to hurt them. There is no evidence that I know of that indicates Spoilt will be more suceptible to genetic "malfunctions" or health issues because he is a bluie. I have 12 year old bluie here now that is in as good of shape or better than some of her younger counterparts. Don't anticipate problems based on his color.
As far as the extra calcium, I doubt if there is any harm there either. NOW, I will say that the cavalier way calcium supplements are recommended by some does give me a fright. Too much calcium can definitely cause problems and that I would defer to veterinarian supervision only. Supplementing calcium via multi-vitamin supplements and dairy products <IMHO> is a much safer route to go and one I utilise.
Debbie