If a custom now-date format ends with a date-variable that holds text (like %a,%A,%b,%B,%p), it can match too many chars.
And when it does match too many characters, those extra characters will always be removed upon any date-conversion.
An example using "%Y %d %B>%Y-%d-%B" (to just change separators) could rename like...
2024 19 MayOnVacationInSweden Archive ---> 2024-19-May Archive
The workaround for now, is putting the extra-text into your now-date and the new-date formats.
Everything else seems to be fixed with Reformat Date, as long as your names have valid dates.
Many thanks for the latest improvements!