Maybe the provincial Archive for Südtirol /
Alto Adige in Bozen / Bolzano should be of inters for you (they have microfilms for all their parishes - which means, also the LDS should have microfilms): From the five people named
Loss, that I found in 19th/early 20th century
Linz, at least three had roots in that region, now belonging to Italy: Ottavio
Silvia Loss, Johanna
Loss (married
Angerer) and
Orlando Otto Loss. I also found a Maria heresia
Loss (married to
Angerer in St. Florian) and a Elisabeth
Loss (married to Aspelmayer, already in 1809 in Ebelsberg).
(Hope you don't mind me answering in
English, my Portuguese is less than bad)