Problems can also be when backporting fixes, because if a line was changed for a spell fix in variable/function name or in the comment and the code fix changes the same line or adjacent lines, then backporting fails because it does not matches the context in the file.
So sometimes backporting typos can help, but if it is a continuous work that results in hundred of commits it becomes a big overhead to track everything, what was in old or new code, what was backported or not, etc ...