Information on Rosén is extraordinarily scarce. He made his debut at the Royal Opera House
in Stockholm on 18 September 1949 as the Second Priest in Zauberflöte. He stayed at that theater as a permanent member until
1951, and made occasional appearances until 1955. His only main role was Rodolfo (4 performances); otherwise, he sang for instance
the Messenger in Samson et Dalila, or the Lampionaio in Manon Lescaut (to Jussi Björling's des Grieux).
Whether he sang anywhere else or ever again in opera, I cannot say; in any case, he sang a lot on the radio and on record, but
was primarily a crooner, although he sang also Alfredo on the radio in 1957, to Margareta Hallin's Violetta.
His career cannot have been long; his latest certified recording date is 1958, the latest possible (but not probable) date is 1963.
Reference 1, reference 2, reference 3: 78opera.com (defunct)
