This seems to be an issue of justice more than an issue of forgiveness. Your colleague seems to equate forgiving with just letting something go. She may be using this view of forgiveness as a way of not changing her own behavior. Because the behavior (lateness to meetings) is disruptive, then this issue needs to be addressed through proper channels and in an appropriate way.
Whether or not your colleagues or you need to forgive her is a different matter. Is her behavior causing resentment? If so, then your forgiving is reasonable. If her behavior is merely annoying, then correcting the behavior may take care of the annoyance and so there will be nothing to forgive.