Stars are not Planets

[Mawlzy]

As FF14 exists in an alternate form of Earth, with it's inhabitants spanning the equivalent of tens of thousands of years in technological development across the various regions and races at the same time, it's not a far stretch to have ones call different celestial bodies all "stars".
So, to the OP, yes star is a valid term for a planet in FF14 megaverse.

Where all this falls down is that key players in FF14 have undertaken interstellar travel. As such, the distinction between a planet and a star -- initially muddled by planet-bound observers -- would not only be very obvious to them, distinguishing the two would be a matter of considerable importance.

That said, the fact we're forced to deal with impossible day-night and seasonal cycles is probably a bigger deal.