Advance and retard are relative terms, depends what you're talking about. We might all be right. Two stroke variable does the opposite if four, now why is that?
If you had an air leak the jetting would be weak. Only continue to retard the timing if the plug chop at the target rpm looks good. Too weak it will be detonating and too rich it will seize. Only retard the timing under Goldilocks jetting conditions and nothing bad will happen.