Not to question what some sites like Ys Music files state, but the original game (PC-88) didn't have a staff roll (
Youtube,
Niconioco), and Kawai even says the existence of him wasn't opened in those days...
There are also quite a few dogmas about Falcom people nowadays put as facts, yet, as decades have passed, we have too little to either back or question them (e.g. "Palace of Salmon" was composed by Nagata, not Koshiro).
The only reliable source on the earlier Falcom I know of is a game guide book which allegedly revealed the composer breakdown of Ys I, although it's now almost impossible to get it.
EDIT: Actually, the thing about Ys I was real. Confirmed.