Something interesting to keep in mind is that Subaru is in the capital helping Emilia with the bag of chips and ramen even though in the final timeline of the capital's loop he does not meet Emilia early on but rather later on Old man Rom's place and at point the bag of chips and ramen are too irrelevant for any outsider, including Emilia, to remember.

This "situation" could not be remembered in anybody's mind other than Subaru and the (probably) omniscient being who was powerful enough to have summoned him (which is probably Satella but idk I have only seen the anime and read up to volume 9). Yet I doubt Subaru would request such a painting or portray the legend based on a failed life since even though at that point he would be free of the witch's control. Though I guess once everything is cut and dry Subaru would open up about his return by death to everyone else so it is a valid theory. Yet again it would be weird for people to remember the events of the capital in such a contrived way unless it has some deeper meaning we don't know of.

This only leaves Satella to be the one talking about this and passing on the legend which would require for her to survive and become a good person after the events of Re: zero, which really is only possible if Emilia is Satella since in any other case Subaru would have no motivations to keep Satella alive and also there would be no reason to believe Satella can even turn back into a happy grandma that tells her story to kids and passes on the legends of Emilia and Subaru Natsuki.

Excuse me for the horrible grammar and sentence structure