URLs with special letters such as åäöüïëÿ dont work
That's right. We do not support internationalized domain names the moment. What's the domain name you wanted to test?
IIRC it was päivyri.fi
There's a workaround you can use to test such sites. Because internationalized domain names are internally converted to ASCII anyway, you can use a Punycode converter to do that first before you submit the name to the SSL Labs test.
Here's one converter you can use: http://www.charset.org/punycode.php
The domain name you sent is converted to xn--pivyri-bua.fi, which then works with SSL Labs.
In this particular case, however, it seems that the internationalized name is not supported in the certificate. You can simply test the non-internationalized name:
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