Import the this sample file that contains the custom validation formula
=ISNUMBER(MATCH("*@*",A1,0)) in the Server Import/Export Demo. The following error is thrown and logged on the developer's console:
Can't handle character with code: 64 (input: \"ISNUMBER(MATCH(\"*@*\",A1,0))\")"
Opening the file with the built-in open command works as expected as well as hardcoding the formula - REPL