Pharos is rather simple:
The name Pharos is still used as the noun for "lighthouse" in some languages, for example: Albanian, Catalan, and Romanian (far), French (phare), Italian, Galician, and Spanish (faro), Armenian ("Փարօս/Paros"), Portuguese (farol), Bulgarian (фар), and Greek (φάρος)
I imagine we'll learn about the designation "Sirius" or it's a simple nod to the brightest star in our non-Eorzean night sky.