Two things to be suspicious of -- not many people made the reverse immigration trip from Maryland back across the Atlantic to Germany. And Maryland was not founded until 1634, so any Maryland date before that is provably wrong.
It doesn't fit your dates, but a John Barry is mentioned as "a friend" in the 1705 will of Marcus Brandt of St. Michaels, Barbados. Marcus was related to a Randolph Brandt, who was born in Barbados and died in Charles County, Maryland.
Of course the major possible confusion is with another John Barry who lived a hundred years after the John you're trying to find -- the later John Barry was a hero in the Revolutionary War and founded the United States Naval Academy.