They don't transpose the strokes, they just forget how to write the character entirely, even if they can read it perfectly: https://en.wikipedia.org/wiki/Character_amnesia
I live in Japan and I have seen it happen many times, suddenly the person needs to stop and check the character in their phone or a dictionary. I have never seen it happens with an alphabet-based language. Sure, you might not be 100% sure about the spelling, but you can always approximate it and write something.
Every single Japanese person who I know has told me how much a pain in the ass their language is to read and write, and how they wish it was simpler, but shoganai.