Also used in Spanish, although this name is rare in Spain, with only 67 bearers (source: Instituto Nacional de Estadística).This name is more used in Latin America. (https://forebears.io/forenames/valdemar)
Valdemar is also Czech and Estonian. The name day for Valdemar in the Czech Republic is May 27. The name day for Valdemar in Estonia is April 18.Source: https://forebears.io/forenames/valdemar
https://www.behindthename.com/name/valdemar/top/brazil
https://en.m.wiktionary.org/wiki/Valdemar#Portuguese
https://forebears.io/forenames/valdemar