while trying to add a website with a URL containing a “umlaut” (mutated vowel, i.e. ä,ö,ü), I got an error on adding this Website (URL-error). So I tryed to at this Website using the URL in punycode- and got no errors. Afterwards, I edited the URL in that way, that I (1) clicked on “edit”, (2) deleted the punycode url and (3) added the domain containing a umlaut and (4) clicked on ok … no error aoccured.
So, I suspect an error exists, because umlaut-domains are accepted (an tracked) and can be defined as the URL of a Website to be tracked - but only on editing the setting for a defined tracker but not on initial defining a new tracker.
Hope, it helps.