I think i found another RSE hint.
In the Lumiose City Museum there are only random paintings or paintings about Kalos but there is one painting about Mr. Briney the captain from RSE
Edit: Also there are Paintings from The Regions Johto, Sinnoh and UNova but no Kanto or Hoenn but i will check again
I think it's cuz the last regions on the ds were unova, johto, sinnoh
But Kanto was available in HGSS and i still think it is kind of odd.
Just like the one person not telling me from which city he is but that i have to see it myself. I think it was in the harbour city