Yeah, there are a number of countries that have three vertical bars on their flags. Will be a bit trickier but not that bad, I suppose. Might take some trial and error.
I treated the UK as one country. Although Wales, etc are in the OOTP database so that would certainly be doable. I used the list from the Confederation of European Baseball
Confederation of European Baseball - Wikipedia, the free encyclopedia
but eliminated some of the smallest countries (e.g. San Marino) and Israel (not in Europe) - which means I probably should do a Middle East league as well.