Similarly, my grandfather was born with first name KALMEN but it changed to CARL in the USA. Which name should I use for him?
Thanks for any insight,"
Everybody has this problem, if they have immigrant ancestors. One of my ggrandfathers was born Baruch, in Amsterdam, Barnett in London, and Bernhard in NYC.
Any good genealogy program today has Aliases as an option you can use. So this ggrandfather is, in Legacy Family Tree, Bernhard Laguna, with aliases Barnett Lopes de Leaǒ Laguna, and Baruch Lopes de Leaǒ Laguna. Which is the 'primary' name and which is the alias is up to you - you can swap them, so it doesn't matter.
Online programs are more difficult. I don't know of any that has aliases, so I use, on Ancestry, "Bernhard Barnett Baruch" and "Lopes de Leaǒ Laguna", as Ancestry will look for all parts of a name.
Addionally, for you, you may want to use the proper Polish KAŁMAN, although I don't know if it matters.