There is a visual cue. If you look at the character portraits in the top left, you will see three circles immediately below the picture of each character. These light up showing you how many source points each character has (up to three).
EDIT: on rereading your post, it seems you are also referring to enemy characters. And you are right that there isn't a way to check that. Sorry.
Last edited by BemusedBear; 25/09/16 04:44 PM.