The Taiwanese rating was removed shortly after, but it confirmed what the Australian rating originally said.
The ratings don’t say what the collection actually is, though the name is likely a pretty good indicator. Konami published Castlevania: Circle of the Moon, Castlevania: Harmony of Dissonance, and Castlevania: Aria of Sorrow during the Game Boy Advance’s lifetime.
Presumably, the collection would include all three of these. It’s possible Konami might exclude Aria or put it in another collection, though. Its direct sequel, Dawn of Sorrow was a Nintendo DS exclusive.
Nintendo usually hosts a Nintendo Direct in September, so a Castlevania Advanced Collection announcement could happen sometime this month. Meanwhile, we’ll have to content ourselves with Castlevania soundtracks on Spotify.