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).
I wish to thank Daniele Godor for the recordings and picture (top).