Tbh, I was kinda disappointed about this when learning Japanese. (Am from Europe where probably all languages have named months.) The days of the week had these fancy names but months were just "[number] month". If you name weekdays, why not name months?
While in German months have names, when talking about specific dates (getting a dentist appointment for instance) you often use numerals. Does the 15th of the fourth at 11 work for you?
Despite all her frustration with the language, she speaks it very well. And she's totally right of course, Wikipedia even includes the demonym in the cheat sheet on every country page, just because no one ever knows them.
Sunday is actually the first day of the week. This is the the reason Wednesday is in the middle of the week and is called "Mittwoch" (Middle week) in German.
I prefer Monday as well, but "end" doesn't always mean "last point in a series". it also means the furthest point of something, but could be on any direction, hence "both ends" is a thing. so weekends can mean the two days on either side of the week, Sunday being first and Saturday being last.
I know that Arabic also has numbers for most days, 1 for Sunday, all the way to 5 for Thursday, but instead of 6 and 7 they named Friday "congregation" (the day Muslims congregate to pray together) and Saturday "sabbath" interestingly enough.
I'm in Finland, the week starts at Monday, Wednesday is "keskiviikko" (mid-week), and I always thought it was called that because it's in the middle of the work week. Because naming the middle of the work week is very important, and nobody gives a damn about the calendar in the weekend, because it's time to chill.