JASRAC has some credits (also see
here):
Rockman X3 (SFC): Kinuyo Yamashita (all except 3.01, 3.33, 3.34)
Rockman X5: Naoto Tanaka (all except 5.27, but maybe they just forgot) --ending has extra people
Rockman X6: Akemi Kimura
Others: Capcom Sound Team
So maybe the liner notes have more.
From
here Hasegawa was main in Irregular Hunter X and Kobuchi helped doing all VAVA tracks (I believe new tracks in
VAVA mode only: 11.04, 11.11, 11.13, 11.25; not Rockman X1's 11.05/06, she helped on that mode when the development was ending)
EDIT: liner notes
Setsuo Yamamoto:
- in charge, lacking time asked for help (one track each):
> Satomura (Iwai): Snow Mountain [Icy Penguigo?]
> Kadota (Takehara): tower [Boomer Kuwanger?]
> Tomozawa: Airport [Storm Eagleed?], power plant (asked for another) [Spark Mandriller?]
> Horiyama: password
- rest is him, "probably", 28 tracks counting them
- sound designer: Joukagi (instrument/hw help, etc)
Kinuyo Yamashita: X3
Toshihiko Horiyama: X4
Naoto Tanaka: X5~X8 synth info
Yuko Komiyama
- X7: Awake Road Again~Highway Stage
- X8: main
- Command Mission: help
Shinya Okada
- X7: Combination~vs Mega Scorpio, Stage Select 1
- Command Mission: main, "Fight! X"
- X8: guest, "ARMOR ARMARGE STAGE" arrange
Kento Hasegawa: Irregular Hunter X main, +20 tracks (bonus movie Day of Sigma?)
Mitsuhiko Takano: Soul Eraser (music-making comments)