From what I remember the ī when spoken sounds like jenteeee elongating the i at the end. So when spoken as well as written with a ī the word that has the dash has a "and the" added to it.
Yes, I think you are right, elongating the last vowel works as an "and the" abbreviation.
But is it in any way wrong to go the long way, and really write "se" for "and" and not elongiate the vowel? I thought this might be something like "cannot" instead of "can't" or "will not" instead of "won't"