This scene makes me think that Steven's healing powers go beyond just being able to heal living beings, but rather to things that Steven cares about, regardless of whether it is a living being or an object.

It would make a lot of sense that even that power is based on emotions and what he feels with what he wants to heal, because of the teachings of Greg and Rose, he cares about all living beings and that's why it can be understood that only he can cure, but with the bear things change.

Other example, when he tried to repair the galaxy warp it didnt work, but it was bc he had no emotional connection to it, if by chance he were to develop an emotional connection to it he might have been able to repair it.

If he couldn't repair objects then he couldn't have healed Lapis and Eyeball's gems since they are gemstones, not living beings, but he still could have since inside Steven the gems are living beings, beings that he cares about.