A lot of more recent otome isekai rofan try to go the subversion/plot-twist route, where the transmigrator FL is revealed as a reincarnation with altered memories (usually done by the resident god to have the FL stop disasters along the way, yada yada)... and this certainly seems to be turning into that trope.
Though, I'm more prone to believe that the novel she thinks this world is actually does exist – but as something Riena herself wrote. I think I've read about 3 or 4 other otome isekai manhwas that go this specific route; a in-universe character (the OG FL, as per the FL's memories... so in this case, Riena) has written the story the FL read in the past, kind of like a fanfiction of themselves in what "their perfect life would be like were they to reincarnate and use all of the info they gathered". Then, both FL and "OG FL" get reincarnated, and you know the drill. So maybe that's another genre of subtrope that exists, and this story is playing into it.
(Who knows, though. I'm just speculating.)
wow, good to know, tysm for the info!! ^^
Is Mc actually a Transmigator? I dont remember her ever saying anything about her old world/life or even her old name… not even like a slight reference like “i know what its like to have siblings” or smth, literally who was MC before this??