But when you get a US visa, the name in both the visual and machine redeable part is written with ä replaced by a, so you end up with three different spellings

But when you get a US visa, the name in both the visual and machine redeable part is written with ä replaced by a, so you end up with three different spellings in your passport. And then you get a Russian visa, where they use a pretty strange transliteration into the Cyrillic alphabet (not the one I would use) and then transform that back to ASCII in the machine readable zone for variant 5. And so on.