It absolutely is. With the twist that ChatGPT 5.2 can now also "explain" an AI-generated Lean proof in human-readable terms. This is a game changer, because "refactoring" can now become end-to-end: if the human explanation of a Lean proof is hard to grok and could be improved, you can test changes directly on the formal text and check that the proof still goes through for the original statement.