I can definitely see where you are coming from since Falcom Music Channel also supports those credits. However, Keishi Yonao has stated on his
twitter that he did work on the game and it's also referenced on this
spreadsheet. It's not uncommon for people to get miscredited or not credited at all, case-in-point
Michiru Yamane was uncredited for King's Valley 2. It's undeniable that some of the
songs in Star Trader X68k have his style, so unless any of the people originally credited come out and clarify then we could correct it.