The math game:
Our server has a bandwith of 1Gbit/s = 125mb/s. This is a theoretical optimum. With tcp/http overhead and other services still running we might be able to provide 80mb/s for downloading patches.
That means 8 players can download a patch at 10mb/s in parallel. Or 80 players can download a patch in parallel at 1mb/s. Unfortunately there is 1500+ players who want to download that. Of course not exactly all at the same time, but you get the problem.
The server network speed is one potential limitation.
This doesn't explain why this particularly affects players outside of the EU. Maybe there are other effects taking place which outside of FAFs control.
We have a similar situation with client downloads. I offloaded these to a private webspace mirror a long time ago which improved the situation for some users and not for others.
Load balancing and CDN:
So why not just put more servers up containing the files?
Well it doesn't just work. Putting in a mirror server with the same files doesn't make it automatically download from it. You need a load balancer in front. Also then you have some backup server capabilities that are not used 99% of the year. So you want to provision a super small one. But still you have to keep the files in sync with the main server, the operating systems regularly updated yadadada. Also doesn't solve conflicts due to the region.
The "enterprise" solution: content delivery networks. Have big companies such as Google, Amazon (AWS) or Cloudflare cache your files in multiple regions and distribute it their.
That is guaranteed to work. But also not a thing we are experienced with at all (this has nothing to do with running server or developing software anymore). So if I look out Cloudflare claims you get it very cheap while Google or Amazon price calculators say it's about 90-400$ a month depending on a lot of variables. I barely believe that Cloudflare can offer it so cheap, so the cheap offers must have caveats we are not aware about. The whole topic is very complex and very intransparent and nothing you just enable you with just a button click (even though providers like Cloudflare try to make this impression).
Fact is we have traffic of 15-20TB a month and traffic just costs money, it can't be free without major pitfalls.
The patch bloat:
Each patch is roundabout 50mb to download.
Do you want to know what the average binary change of a patch is? It's roundabout 100kb.
I know this because from 2017-2019 I spent a 100-150 hours trying to build a better patch system. I actually have a working one, but it went into crazy complexity and exchanged the download speed for speed in applying a patch. I did not take into account that 30%+ of our playerbase runs FAF on 10-15 year old notebooks with the power of a toaster.
There were many discussions about other ways of doing it. But creating game patches in FAF is super complicated consisting of source code from git repository paired with binary files and different setups for different featured mods. Basically it's hell and touching it will most probably break other parts of FAF (especially backwards replay compatibility).
So the "correct" solution would be a proper patching mechanism, bringing down patch size to justifiable levels (maybe 1-5mb with decent patching speed or similar...)
So overall speaking it is a very complex topic on a problem that occurs a) only to subset of the playerbase and b) only on rare occurrences (game patches, partially client updates) and c) it can be solved by the user showing patience and/or trying again at a later time.
Furthermore d) the problem is as old as FAF and doesn't break anything.
My personal opinion on that matter is: FAF has other issues and topics that have a higher priority. Not all of them are [intended to be] known to the public.
We can try to apply some of these proclaimed "cheap and easy" solutions, but my common sense super powers tell me they won't work on the scale of FAF and/or will be unreliable or shut down by the service provider because we excessively use it.