Listening to these versions can help in interpreting the sheet music correctly:
Extensive 32 to 62-page documents containing instrumental parts for clarinet, flute, and other ensemble instruments can be found on Scribd - Misa Oaxaqueña Partes Choral & Guitar Accompaniment: misa oaxaquena partitura pdf verified
This is the "stress test." In almost every free, unverified PDF, measure 25 of the Gloria will have a typo in the Tenor line. The correct interval is a descending fourth (La to Mi). If you see a unison or a fifth, the file is corrupted. Listening to these versions can help in interpreting