@BigAl - if it might help, let me share with you my experience - given that I have two Rose 150 in two different countries.
My playlists which are made with music files taken from my music collection saved in the internal SSD are visible on both devices - in other words, whether I am in one country or the other, I can still see these playlists on the Rose App, meaning that these are always saved as linked to my Rose account.
Nevertheless, I can only play music from playlists which have been compiled/saved in one country.
So - although the SSD contains exactly the same collection and exactly the same amount of music files, the Rose will only play the playlists which have been compiled (and saved) through the SSD installed in that country.
Thankfully, this doesn’t apply to playlists made with RoseTube music videos/files and - whether I am in one country or another - I can always play my RoseTube playlists and this makes sense as the playlist is saved because it is most likely linked to my account somewhere on the Rose servers and I can access it wherever I am.
Hope this helps.