When a Leader Line and/or Border Frame are used the leader line should be (or is most often desirable) perpendicular to the geometry instead the perpendicular location being based on the text justification. When a Border Frame is used it really looks sloppy without manual adjustment. Attached are basic examples, the orange labels show the text perpendicular to the centerline based on the justification, the yellow labels are what would be desirable.

The work around I’ve found for perpendicular leader with single line of text is to use a Left Center justification and modify the text favorite to add a hard return with only a space to create a blank second line of text, but this seems unnecessary. I have not found any sort of workaround when using a Border Frame.