From Halopedia, the Halo wiki
Galgalia is a planet in an unknown star system. Early during the Human-Covenant War, the UNSC frigate Daedalus crashed on the surface of the planet. The wreckage of the Daedalus was later scavenged by the UNSC.
Thus far, Galgalia has been mentioned only in a brief promotional video for the M12 Force Application Vehicle's guest appearance in the third-party racing game Forza Motorsport 4. Therefore, its status as canon is unclear.