[duluca]

I don't think this is about umlauts. Like you said, it is a name. I'm from Turkey and my name is spelled Doğuhan, but as I was immigrating to the US (before Unicode was commonly used) it became Doguhan. A lot of native English speakers struggle with it, almost no one pronounces it right, they misspell even after seeing it written in front of their faces. I did play around with the idea of going by Doug during college, but then I decided that I wanted to retain my unique identity. It took years for some of my friends to stop calling me Doug, but they did change. It'll be okay, people will adapt, umlauts or none. Otherwise, people will do what they'll do. Some idiots still refer to Istanbul (correct spelling İstanbul btw) as Constantinople. C'est la vie