I believe that MW is matching transactions on the description field within an account? And then determining/guessing the Payee and category from that. It would be useful to be able to edit those rules after MW creates them and 'permanently' correct what MW has 'learned', like you can edit the Payees in preferences.
P.S. a regex or a glob match option would be great for us nerds.
Are you referring to manual bank statement import or Online Banking downloads?
We have implemented an algorithm that reads the descriptions and extracts the payees from there then assigns a category last used for this payee. We do constantly think about ways to improve this but we cannot promise any immediate changes.