There is no requirement that such a function behave exactly as the
interpreter that the user has. As with the "corefeval" I proposed the
other day, it is that underlying builtin code that is what the GUI has
interest in. So, the commands that go from the GUI's internal access
bypass that first level of indirection that otherwise would be M-script
overrides, variable overrides, etc. Neither would these commands appear
in the history list. The best way to describe "corefeval" is that
builtins cannot be overriden.