"Luckily I knew both the source and target languages well enough to know it was bs'ing me."
Google Translate does tend to drop words or replace a word with a duplicate of a nearby one. Worst of all is when it misses a negative indicator.
My best mistranslation is -
Allehelgenskonsert - which Google automatically detects as "Frisian" language = "Privacy statement".
When told it is Norwegian it comes up with a more obviously sensible "Halloween Concert" - except the Norwegian word has no "evening" component in it - it is literally "All Saints Concert".
Given the context of a Cathedral choir my guess is that it should be "All Saints Day Concert" - making it one day out - and an interesting confusion of beliefs.