Incidentally, I try my hardest to pronounce Chinese names correctly, as I study Chinese.
You would write “Yang” and not “Young” (assuming that’s their name and they didn’t change it to “Young” after migrating), and you would leave out the pinyin vowel markers.
Since many Chinese carry a western name for the convenience of having something westerners can pronounce, that can be a safe fallback.
What I mean is there's often no way to write Chinese names for people who don't know the language while also being what their owners would used. Yang ends up being pronounced like "bang" instead of "bung" and the between spoken dialects break pinyin even further. Characters are the faithful way but completely unreadable and untypeable to most people. I'd say just use the best way to communicate instead of using confusing symbols out of respect for strangers at the expense of respect for the person you're talking to.
When I see names with strange accents like ő, I just ignore them. Better that than guessing wrong. Of course if it's a real person you have a relationship with, you'd go to a bit of effort to figure it out.
You would write “Yang” and not “Young” (assuming that’s their name and they didn’t change it to “Young” after migrating), and you would leave out the pinyin vowel markers.
Since many Chinese carry a western name for the convenience of having something westerners can pronounce, that can be a safe fallback.