Hot take: There aren't other interpretations of the scene, there are only willful misinterpretation.
This interaction is clearly not meant to be mocking. Sure, Flowery is talking down at Ralsei but not in a way that I think can be truly read as malicious. Also, Ralsei isn't the kind of person who would take offense to be called a princess, so why would it be used as an insult here. (Heck, in this game, it being used as an insult doesn't fit how the world and characters seem to interact with gender. But I could even be wrong about that that doesn't matter.)
Flowery is a character meant to get under Ralsei's skin, so there's no reason to have him use an insult that wouldn't be effective on the character as we know them.
Unless, it's meant to reveal new information, and I doubt the story wants to reveal that Ralsei is secretly a misogynist so... what else would it be telling the audience about this character? a character who is defined by the prophecy as a prince and the shapes everything they do are and allow themselves to be around that? Hmmm...
Why call that character princess like it's a big drop moment? In a game with a non-binary main character and several lesbians? In the chapter where a canonical trans woman is the secret boss. Secret bosses, which usually parallel one of the core trio. Who's the only one of the core trio who hasn't gotten a boss that parallels then yet? The same character who has the most interaction and friction with the character closest to that boss over the course of the chapter.
But I'm getting off track again.
Why would you call that character a princess? Well if you were some sort of flower-man doing it during a scene where you are talking about how much they should allow themselves to be happy, be themselves without worrying about others and try living for themselves rather than following the prophecies rules then you might say it if you wanted to make sure that character knows, you know exactly who they are.
If you were a Game Dev, you might say it to make sure the members of the audience who haven't picked up on all the little hint you've been sprinkling around the game, such as the pink white and blue "princess ribbon" (Ribbons that the game often encourages you to put on a certain prince)
Among other interactions and thematic parallels.
The point is there's no way that this Frame is just a throwaway line, there's too much focus on it, too long of a pause too important of a moment.
And that's not even getting into the drink color, I know it is the color of Kris's dark world outfit but here is the thing, things can have multiple meanings and one meaning doesn't invalidate the other. If it were the only evidence then I would dismiss it too, but in conjunction with the line and just everything else every video on the topic of Ralsei's gender will point out.
At a certain point, it just becomes Occam's razor.
And somehow we've returned to the days of years past, gazing back afixed a past we forgot to see those we called fools were seers in disguise as we look with new eyes.
And ourselves see that...
I'm so sorry, tricycle, or whatever your channel name was.
