So....there are a couple of songs that are missing... It had a limed release at some event in Japan. The others are just gone... only snippets of them has been found
Taken from the Danganronpa Wiki:
It had an initial limited release at Comiket 93, which was held from December 29th, 2017 to December 31st, 2017. Any left over stock was sold to the public starting on February 3rd, 2018 through Water Orion's website.
Sky Blue Canvas- Found S.B.S.A- Lost Essai de Mentur- Found Hope of Despair Found