[kovidgoyal]

Those are all functions that were defined as globals in calibre a long time ago. _ and gettext and ngettext can now be imported perfectly safely. If you are worried about doing so for compat reasons you can do the following:

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from calibre.utils.localization import ...
else:
    the original code

This should work with all type checkers. As for load_translations() that's specific to calibre plugins and is documented in the manual https://manual.calibre-ebook.com/creating_plugins.html