I am trying to create a freeform question to label several areas of a diagram. I added a few text boxes but it looks like I have to use the same correct answer(s) for every box. Am I missing something or will this only work with a single entry?
A graded text-entry question can only evaluate/score 1 text-entry field. When you insert additional text-entry fields, Form View gives you the option to indicate which field to score.
You can indicate more than one acceptable answer for the designated field. But there's no standard question for grading multiple text entries.
As an alternative, you could disguise a multiple choice question by hiding those response buttons, or create a freeform one, with the buttons off the slide. Then use triggers to evaluate your text entries and then a trigger to turn the appropriate multiple-choice button to Selected. You could even give partial credit if the user enters some correct answers.
This post has a file showing how to give partial credit for multiple-response questions. It's not exactly what you're doing, but it might help clarify what I'm talking about.