Theodore was in much less of a state than Barty; he knew it was a good thing that Rosier had woken up, knew that memory loss could easily be temporary. He also had an enormous amount of faith in medicine. Still, he would have had much more faith in full recovery of these symptoms if Rosier had been the healer, not the patient.
And if this were not a new experience for him. Burns, he had seen, cuts and bruises, even some bonks on the head, but actual brain damage - damage that wasn't inflicted by a spell he could simply reverse. That was new.
He wanted to confer with Gina about what they could do for him, because he wasn't sure what the first step was; he either needed to consult a more experienced healer or a book. But he could set about making Rosier more comfortable, now that he was awake; regular pain medication, for one thing.
He had kept on believing that Rosier would wake, and he would continue to believe in a full recovery. Waking up from a comatose state was the first step to allowing them to heal him.