I think this issue is actually quite a large problem. I somewhat regularly get PMs from users with (allegedly) fast internet that are running into extremely slow downloads trying to download coop/mods outside of patching periods. I have no idea how often this is actually due to the server's bandwidth being saturated, but I suspect it is somewhat often. Considering that the percentage of people who will message a mod (and me specifically) about an issue is typically an extraordinarily small percentage of people who experience this issue, this problem may be widespread outside of patching periods. (Someone with server analytic access can tell me if I'm totally off base if the bandwidth actually isn't saturated outside of patching periods)
We should also strive to provide the best user experience possible during patching periods. Creating a 1-2 day window where FAF is basically unusable for users outside of Europe every few months should be avoided if possible. We should not expect the average user to use some random mirror that no one knows about. If players can't play FAF, they go somewhere else and they might not come back. If we have someone willing to set up a CDN that costs $400/month to avoid this issue, we should do it, we can afford it. Will it eat into the the tournament budget? Yes, but ensuring the best possible UX is most important.