In general, I can't seem to find proof that Sky used any of the currently entered titles when any of the episodes in the show were released. As far as I can tell, Sky currently lists the episodes without titles, and the titles were only added on TMDB in September 2022 (four years after season 1 aired and a year after season 3 aired).

When I looked I could not find any examples using the changed spelling. However, I could find plenty of examples of how they were beforehand. Here are two examples but there are more https://www.tvguide.com/tvshows/britannia/episodes-season-1/1000199784 and https://en.wikipedia.org/wiki/Britannia_(TV_series).

However, considering how sky have listed them https://www.sky.com/watch/title/series/britannia/britannia/episodes/season-1/episode-1 there could be a case made to list these Britannia 1, Britannia 2, Britannia 3 etc... This is how https://www.nowtv.com/ie/online/britannia/3bcd32ded75e0610VgnVCM1000000b43150a____/7e14590c5cbf0610VgnVCM1000000b43150a____/seasons/1 list them. Also Episode 1, Episode 2, Episode 3 is also used on various places, see https://www.amazon.co.uk/Britannia-Season-01/dp/B07BN75XGB and https://britannia.fandom.com/wiki/Category:Episodes.

Regardless, the changes made by the user on May 18, 2024 appear bogus to me as they look to just want the US spelling.