The set painted on the walls west of Slitherbough (the ones I posed above) couldn't have been painted by anyone from the Ancients or Ronka because that would require them to have knowledge of Ardbert's adventures and victory over Shadowkeeper.
That painting was done by someone Ardbert actually knew, and all three paintings there are separated by thousands of years.



The Ronka discovered the first one and had the second commissioned to stand alongside it. The first painting there bears some similarity to the three in the Ravel, but given the professor's painting is also similar we can't really assume all four were painted by the same person.