AFAIK, the installer tries to make a ‘best guess’ at appropriate mirrors, and mostly succeeds. The Welcome button access is an ‘extra’ - and while it will always work, it is rarely needed…
I can’t count the number of installs I have made during ISO testing. One habit I developed is to always update the repos with the Welcome app before starting calamares.
I’m sure it has saved a lot of troubles down the line.
I also have a problem because my home connection is so slow. 10s is not enough to contact the mirror and test speeds. It just gives me 0kb and just adds the usa mirrors in my list.
I know I could do it via cli and reflector, but is there an easy way to change the test time on the eos welcome app, like from 10 to 30 s?
i just saw that there are some options on the right side, just open Update Mirrors and look for your self, maybe you can tweak with some other settings and also reflector --help shows some additional options,too.