I have found this a very interesting project.
So have I. My main interest in Knoppix and Linux in general is that I might learn something from using it. I still use Windows for much of my tasks, but I am using Linux much more frequently. I have been somewhat discouraged using certain functions in Knoppix such as the BitTorrent client, since I have just had much more success using it in Windows. It is interesting that you mention the "Old IBM Mainframes", since my first experiences wre with an old IBM 360 and a Digital PDP8i. Learned a little about Cobol and Fortran, very little. That knowledge has since leaked out on my pillow over the years.

I just did a little experimenting and Installed Azureus on a Windows machine alongside BitTorrent 4.0.4. I noticed that what I said about the Local and Remote peers to ring true, but most evident with the DVD Torrent. I tried the DVD Torrent with a misconfiguration of NAT by mis-setting the router. Fixed it and then went over 300K within minutes. Tried the same thing with the CD Torrent and saw almost no difference in speed either way. Just a little quicker with the Local and Remote peers listed. Only about 40K difference. I did not complete the downloads, but it told me what I needed to know. It acted the same way whether it was a router configuration error or a firewall issue. I basically did the same thing with the Azureus AND BitTorrent programs and the results were VERY similar. The main point here is that you can get good download speeds even WITH misconfigurations, but it gets better when it's all correct. I guess the difference between the CD and the DVD Torrents is due to the fact that the DVD Torrent just has many more parts of it to acquire and that if you have exposure to a wider set of peers, you will do better.

I will be searching through the iptables information and maybe will have some time to try downloading with Linux. If you get it figured out, please post your results. I would be interested to see if it is relevant. It may only be one part of the puzzle. I believe that you can always just re-download the EN version to a different target.

I did like the Port Checking tool in Azureus, but the program in general seems to use an inordinate amount of resources, even with the latest Java updates. It appeared to lock up on occasion if I tried to do something else while downloading.

Linux can sometimes be a bit more difficult if you are a casual user.
I think that explains most of my troubles with Linux. If I really pressed myself to use it exclusively, I'm certain that I would be finding the solutions to a wider variety of issues. My proficiency has increased over the years, but I am in no way fully competent or comfortable with it yet. I have a much better understanding of Windows, but that is because I have been pressed to use it while employed. There is just not enough time in the day to do what I would like to, and Linux is one of the interests to suffer.