About the romanization of the pianist and conductor of the choir bonus tracks, these are my sources:
岡本仁 = JIN OKAMOTO (
Source 1) (
Source 2)
法島晶子 = AKIKO NORISHIMA (
Source 1) (
Source 2) (
Source 3)
If you check into these sources you'll see these two musicians have been very active in choir performances (in the case of the pianist is her specialty), although most of the info is in japanese.