Thanks for the links, I will focus my research on the towns listed.

I found a record for Mauro at Find a Grave with the following information

Burial Utakarra, Greater Geraldton City, Western Australia, Australia
Birth 13 November 1895
Death 14 January 1964

https://www.findagrave.com/memorial/186918521/mauro-valenti

Could not find the death certificate ...

I'd like to find information about Francisco Uderzo (my 2nd great-grandfather).

His death certificate states he died in Carazinho, Rio Grande do Sul, Brazil, in 1917, and it is implied he was brazilian. However, there is a register for Francesco Udezzo, italian, in São Paulo, Brazil in 1889, being ...