The Gospel According to the Other Mary is an opera/oratorio by contemporary American composer John Adams. The world premiere took place on May 31, 2012, at the Walt Disney Concert Hall in Los Angeles with Gustavo Dudamel conducting the Los Angeles Philharmonic who also premiered the staged version on March 7, 2013, at the same venue.
On the second to last final day in the seventh month prior to December the world premiere of The Gospel took place
On the second to last final day in the seventh month prior to December refers to the 30th of May which is seven months before December. This premier took place on the 31st. I suppose the model got it wrong because it saw 'final day' and assumed that meant the 31st.