If you have to take each track individually, here’s how I do it. Very quick and safe. You will need to open the original N4 projects though?
First copy each project to a new location. Next, put all the tracks in record and record a short section before the start of the song from a convenient point - a bar line is ideal. (You can prob draw an empty audio part instead of record, but I like to record)
Select All. Bounce Selection. (make sure the tracks are titled with their contents, as the new files will be carry the same names.
In the Pool, remove unused files to trash. Empty Trash.
The Audio folder should now only contain the new files, which all start at the same point and can be imported to any DAW. It is worth checking in your Audio folder because often there are extra files which should not be there (Empty Trash is a bit buggy in this respect). They are usually Size 0kb. Delete these.