I'll just add the links to the soundtracks in question:
Nukaka's Marriage
https://ototoy.jp/_/default/p/14880
Telomere's Hats
https://ototoy.jp/_/default/p/14881
Calcino's Gift
https://ototoy.jp/_/default/p/16444
Interview which lists the members I listed in my OP.
https://ototoy.jp/feature/20100808
eBook example:
https://www.youtube.com/watch?v=OJSpq5Qn0xE
And if no, well... it gives some exposure to something Mitsuto and the others worked on.