question about colors
different courses have different colored badges. Like Russian is blue with Saint Basil's Cathedral, Japanese is blue with Tori gate, and Swedish is blue with Stockholm city hall. Meanwhile, German is black, with Brandenburg gate, and so are Klingon and Valyrian. Irish is however green with Blarney castle. There are some yellow ones as well.
Do these colors mean something, or are they completely arbitrary?
From what I have observed, they are decisions that are made by staff, and it is in accord which color they feel is most appropriate for the "national" character of that course.
They do not have an secondary meaning of any kind.
If you go to:
You will see that some courses also sport red.
I think they also like to use different colors to make things more attractive and interesting, and well colorful.
I like the colorful nature of them myself.