One branch of Justo Rufino Barrios' family settled in Switzerland, in a place calle Kusnacht near Zurich. His Granddaughter, I think, married an austrian or hungarian man by the last name of Reissinger and they had a child, named Stefan, who was born in Manhattan, N.Y. around 1950. The couple subsequently divorced and Mr. Reissinger has in the Lake Placid area in the early 1980's managing some resort, with a second wife. His ex-wife returned to Kusnacht and raised Stefan there, with the help of a maiden aunt who looked very guatemalan. I met Stefan in Oaxaca, Mexico in 1980 and he told me this story. He was traveling back from guatemala and on his way to New York. I have no idea whatever became of him, but I bet there are ways to track some one down that can give you more details. I think Stefan was born in the month of june (he told me he was a gemini) and he sometimes spelled his name Stephan, although his travel docs. were spelled the other way.
For some info on President Barrios' life, you might want to check Google.
I would love to know if you find out any more. Good luck