Sydney is Sydney.
Sydney Henegar is spelled the same in German as it is in English
Sydney Fairbrother's birth name is Sydney Tapping.
Sydney's name is just Sydney. It's not spelled differently..
Just like you do in English
Sydney Booth's birth name is Sydney Barton Booth.
Sydney Spies's birth name is Sydney Elizabeth Spies.
Sydney Chaplin's birth name is Sydney Earl Chaplin.
Sydney Carter's birth name is Sydney Bertram Carter.
Robin Sydney's birth name is Robin Sydney Heymsfield.
Sydney Wolofsky's birth name is Sydney Lynn Wolofsky.
Sydney Wong's birth name is Sydney Devonne Wong.