The OPC decision carries weight with me. While all synods and councils can err, and have erred, the OPC is not known for downplaying doctrine.
For clarification, because I don't have a copy at home, do you mean the OPC/URC Trinity Psalter Hymnal or the OPC Blue Trinity Hymnal or the OPC/PCA Red Trinity Hymnal? I assume you mean the joint OPC/URC product, and if you do, that goes double. The URC is even more known for theological precision in its songs and that was part of the issue of why the URC refused to accept the CRC's 1987 Gray Psalter Hymnal, arranged a special reprint of the CRC's older 1959 Blue Psalter Hymnal, considered working with the Canadian Reformed, and eventually decided to work with the OPC to produce what is now the Trinity Psalter Hymnal.