I imported the Thunderbird holiday calendar (https://www.thunderbird.net/en-US/calendar/holidays/) for Finland and noticed the frankly horrible localization. The translations for international holidays were absolutely terrible (seriously, even modern machine translation could do better!) and local holidays were even missing. However, I couldn’t dig up any place to contribute to the translations or the calendars in general.
So, how are the holiday calendars maintained and where could I contribute?