the film from Kaouther Ben Hami-''The voice of Hind Rajab'' (there follows a question mark here but my keyboard is old and dusty and doesn't perform on some symbols ).
Google says: In England , "fortnight" and "two weeks" are used interchangeably to refer to a period of 14 days, while in Welsh, the term "pythefnos" (meaning "fifteen nights") is used for the same duration, which includes both the start and end days, effectively counting both the first and last days of the two-week period......
You are more or less there Yorkie. Wrong in one respect in that the English word fortnight originates in the Anglo Saxon word feowertiene niht (ie fourteen nights) - the Saxons measured such things in nights not days. The Welsh word for a week 'Wythnos' means 8 nights and thus 2 of these would be 16. Although, as you say, the celtic languages do have words for a 15 night period. So assuming the Saxon fortnight to be 14 nights the difference would be one night (or two if you use the Welsh word for a week and then double it). English is unique in that it has a word specifically for fourteen nights - others have words for fifteen, or have to use two words to describe it eg. German (Zwei Wochen). Take it away !
