You are assuming that with your (man's) limited understanding you can discern "typo's" in the first place.
If IDists can discern design from nature in DNA, we can certainly discern typos. Or to put it another way, if we cannot, because of our human limited understanding, discern typos in DNA, what chance does ID have of discerning design from nature, especially since a designer could make design appear to be nature, and nature could very easily appear like design?
If we can't understand "typos" how can we possibly tell design?