Comment 4 for bug 37138

I'm well aware of how locales work, but you can't legally set en_FI as *any* of those locale items because that locale simply does not exist. The best the installer could possibly do is set fi_FI.UTF-8 for some of those items, which would leave you with a bizarre mix of English and Finnish in places (e.g. dates). Having selected the English language, I'm afraid you need to select a country where a locale is defined for English in order to get good results.

The keyboard point is valid, since that's internal to the installer.