Friend Mariana.
Don't you have other data the aviator's Krohn?
It is very little what you can find alone with the last name.
I show off that the name "Juan" it is very Latin for a person born in Germany.
Maybe he used that name like a family form among their friends in Argentina.
In the idflieg page,
www.idflieg.de, meets some data on personal with that last name:
The first, pilot:
Leutnant d. R Krohn Flugzeugführer (Pilot)
Source: Vom Lilienthalgleiter zur fliegenden Annelise Author: Wolfgang Miertsch, p. 91
The second the same year that you mention died:
Hauptmann to. D. Hellmuth von Krohn, born 03.08.1891 died 08.06.1924 Source: Ehren-Rangliste gives ehemaligen Deutschen Heeres, Author: Deutsche Offizier-Bund, pag.480, -489 - Grabstein Kron, H. v.
The third are:
Unteroffizier Karl Krohn, Feld Flieger Abteilung? Source: Flugsport 1915, VII. Jahrgang, Author: Ursinus, Oskar. P. 703
Maybe having some unit, military range, period of service, you could find more data.
I wait to have helped her a little.
Suerte en tu búsqueda!!
Dario