I'm pretty sure this is a textual error you may want to fix:
On Page:
https://api.backdropcms.org/api/backdrop/core%21modules%21taxonomy%21tax...
Incorrect:
Do not call this function, use taxonomy_get_term_by_name() instead.
Should be:
Do not call this function, use taxonomy_term_load_multiple_by_name() instead.
Comments
Indeed! Thanks @JugglingCoder.
EDIT: Added an issue for this: https://github.com/backdrop/backdrop-issues/issues/4299