He can regenerate body parts like COAT but didn't regenerate his arm due to lack of chakra and lack of experience with medical jutsu and Mokuton. Tsunade made him a new arm with hashi's cells meaning he should have the same regeneration feats as a Juubi Jin
Tsunade made him and Sasuke an arm from Hashirama's cells, I am curious to aee if he gained anything from it (there is speculation of him being able to use mokuton now).
He never got it back the arm he is shown with is one made from Hashirama Cells that Tsunade created herself also the same very arm was made for Sauce which he denied wanting and left without receiving it.