I don't agree with this, or that the ROTJ line is a problem. In a universe where Force ghosts and disembodied voices are a thing, I don't have any problem justifying Leia's memories as Force impressions that she experienced well after Padme died. She recalls them as memories because that's the framework she had to work under as a child, not understanding the Force or how it could work.
For a related comparison, though not precisely the same thing, check Cal Kestis in the new Jedi Fallen Order video game. He has the Force related power to experience events from the past by touching objects that have absorbed Force impressions from their owners/users. Just assume something similar for Leia in regards to her mother and the ROTJ line works perfectly as is, and even acts to further tie her to the Force and her Skywalker heritage.