My goal is to substitute empty cell with a “0” value. I’ve found the way, however I think that it could work much easier if this function was integrated within operations block. A “delete empty data” block already exists, I could imagine substitute "0" for "nulls" command somewhere there.
I've found that the Search/Replace will work for this and you can put this into the operations, also lets you decide which character to have it replace with and can be done against multiple or selected fields/columns
Leave the "Search for" blank and check "Match entire cell". Enter the value you want to use to replace empty values (in this example "0") in the "Replace with" box.