frandle = flandre

btw

I'm pretty sure it's supposed to be Fran-something anyway, because Fran is pretty common shorthand for a girl's name. Thanks, "English" speakers.

It may be coincidental, but "Flandre" is the French name for Flanders.

It's a decently common way to see her name spelled, as it's closer to how the Japanese would pronounce "Flandre." That is, like "frahnd-lay." I seem to recall it might be from a different romanization method too, but I know very little about that.

/flã.dʁ/

Roughly, "flon-dr". (the a is combined with the n, resulting in a nasalized 'a' that sounds sort of like "o" to an English speaker.)