The word “summam” certainly wasn’t pronounced as “sanum”; there’s no ‘an’ sound whatever (I don’t even hear that in the unamplified YouTube audio). If you listen attentively the ‘u’ is actually pronounced like the ‘ow’ in ‘town’, which is constant with his pronunciation of ‘spiritus’.
Nonsense. Bishop Sanborn, Father Chazal, and I all concluded that he said mysterii sanum. We're all aware of pronunciation differences and this was not covered under that umbrella. Bishop Sanborn and Father Chazal both speak a number of modern languages and have heard a broad range of Latin pronunciations. I myself studied Latin formally starting with: 4 years High School, 4 Years College (B.A. in both Latin and Greek) and 3 years of Graduate School at Catholic University of America. I taught undergraduate Latin at Catholic University and also taught Latin at St. Thomas Aquinas Seminary while I was there. This was not a pronunciation issue by any stretch. He was obviously confused and didn't recognize the word "summam", just like he didn't recognize that "in sacerdote tuo (in sacerdotibus tuis)" were listed as options to be chosen from depending upon whether there was one consecrand or more than one, just like he didn't understand that "comple" began a new sentence and a new thought.