Thank you all for your replies!
I now know it can run without any problems on Windows XP and luckily on Windows 10, if you copy and register one or two ocx files. It seems it won't run on Vista and probably on Windows 7. The error message in Vista is "Unexpected error", so you can't tell which file is missing. I tried a nice Microsoft program called Dependency Walker, that shows you any warning and errors. It shows a warning about an Internet Explorer file. After I updated that file (which was very difficult, as it's a system file that you can't change even on safe mode), I managed to break things in Windows like Control Panel, so I just undid the changes.
Never mind, as the program can run on Windows 10. In fact, if you want to translate FOTAQ, you have to run Sparky one time to extract the files and then whenever you want to insert them back. As the game is already translated and just needs some corrections, I don't need to use it often. My PC has Vista, my kids' PC has Windows 10, so I just use it only for extraction/insertion of files.
At some point I will just upload installation instructions for it :-)