Reportedly, on the occasion of jimoku (ceremony for appointment of court officials) in 1129, he made a document in which the position to which MINAMOTO no Moroyori was appointed was erroneously transcribed and the jimoku was held again (Moroyori was Munesuke's maternal uncle).
1129年の除目では、宗輔が源師頼の任官された職務を誤って書き写した公文書を作成してしまい、除目のやり直しが行われた事が伝えられている（ちなみに師頼は宗輔の母方の伯父にあたる）。