Entering payment does not match the locale
When filling out certain information, like birthday or address, such as on the payment registering page: dashboard.twitch.tv/u/USERNAME/settings/revenue/payout-onboarding
Some information like birthday does not match the locale. When set to Swedish (sv), the birthday is incorrectly given as MDY. Thanks to the simplicity of the HTML-code, it is very easy to simply reorder the divs to match the order of the locale.
While the month-name is written out, it's more a matter of the quality.
Another issue is the address-field. To be able to enter a Swedish address, the letters éåäö (as wellas ÉÅÄÖ) must be accepted. International address can't simply be restricted to A-Z. Ä and A aren't the same letter, and you can't replace one for the other. It would be like rejecting W as a letter* and force you to write "Vashington" or "VVashinton".
- In Sweden, W wasn't considered a separate letter in the alphabet until recently

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PonPonTheBonBon commented
I do understand that it is possible to replace Å with AA, Ä with AE, Ö with OE, it just makes is simpler to allow ÅÄÖ in the first place. Do note that this doesn't work for Finnish and other languages.
Another example is in Hungarian where É is replaced with E' but Ö is replaced with O:, but : isn't a valid character in the input-field, preventing the ASCII-style writing of Hungarian as well.
Easiest is to use Unicode, and expand and allow at least the Latin-1 extended letters: À-Ö, Ø-ö, ø-ÿ.
Twitch/Amazon requires this information to be correct, but doesn't allow the actual letters to be used, meaning the information can't be correct. So if a Swedish street-name contains Ä, you either have to allow Ä as a letter, or I have to input the wrong information.