Name
"Hyacinth," customarily an English woman's name, is the English spelling of the generic name of the flower – which in German is spelled with a z. 

The subject was a German male. The subject's given and legal name was Hyazinth. German WP therefore uses Hyazinth. A newly published English-language history of WWII in the Baltics, Prit Buttar's detailed and thoroughly documented Between Giants: The Battle for the Baltics in World War II – published by UK-based Osprey – uses Hyazinth in every mention.  To persist in using Hyacinth for this person is an error, regardless of what past (mistaken) practice in English may have been.
Ref.: Buttar, Prit. Between Giants: The Battle for the Baltics in World War II. Oxford, UK: Osprey Publishing (2015).  ISBN-10: 1472807499; ISBN-13: 978-1472807496.

, please do not revert my edits again. Thanks.