I have built 6440 with no real problems in Windows using default English but a quick check on the features I use show the following.
1. I had trouble setting the virtual telscope. Took a couple of reads of the help file but got it in the end. However I left it connected and tried to slew to a DSO using the search button. It did nothing till I disconnected the virtual telescope. I will need to try it on a real telescope as well.
2. Drawing constellation boundaries drops FPS from 30 fps to 7 fps
3. I changed the default const name color to .4,.4,.15 so it stood out better.
4. I only checked the key bindings I use but noticed no problems. There may be still conflicts with other duplicated bindings particularly non USA keyboards