Yes, you most likely have to purchase the Megpoid V3 bank(s) to get the demo files, but it’s possible that the vbs might not come with the files for those specific demo songs. I have Megpoid V4 complete and English, V4 Complete only came with the files for Possibility and not Tasogare, and English came with files for 2 or 3 demo songs.(I don’t remember which ones)
Edit: I now realize that Et Cetera is actually one of Chika’s demos and Hoshi no Kakera is a Miku demo. Maybe somebody gave you the wrong info, but those are not Gumi’s demo songs.
