I'm onto something here. To make the text lines know when they reached the edge, I can have 2 box colliders waiting to signal when overlapping. One stays on the edge where words should never pass, the other is at where the first word appears and increases its width by 3 every time a new letter appears. Because the boxes are centered in the middle, I have to make sure only the right side of the box is the one detecting anything and let the left side go off screen.
This is much easier than the letter-by-letter or one word at a time methods I was trying to force earlier.
