We don't have synonyms for burggraf yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are burggrave.
(n) :
Alternative form of burgrave. [(historical) The military governor of a town or castle in the Middle Ages, especially in German-speaking Europe; a nobleman of the same status.]
(n) :
Alternative form of burgrave. [(historical) The military governor of a town or castle in the Middle Ages, especially in German-speaking Europe; a nobleman of the same status.]