One language is always default and will show for the unchecked ones.
Also note, that for some countries (languages) the week starts on Sunday, for others on Monday.
So I would allow all number that work correctly, and maybe pick UK English as default.
Yes the calendar on my phone (Verizon, USA) has the wrong week numbers too. You can see what it should be for your country from this site Week Numbers for 2021
Unfortunately there is no "Standard for the first day of the week
For most locations week one is the week with 4 days in January.
For others week one is the week with Jan 1st in it and that is why my phone’s calendar uses.
Ron
Samsung Developer Relations
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