Yes Taco Bell does use lard in their beans when cooking them.
When I worked as a cook at Taco Bell one of the ingredients in the beans was lard.
So while the website Taco Bell says they don't use lard in their beans they do use lard in their beans.
The lard in the Taco Bell beans does not mean it's a bad thing and the lard makes the beans taste better as well.
Taco bell food is not the healthiest of foods out their but it's okay to eat Taco Bell food or other fast food in moderation.
I don't work at Taco Bell now so things might have changed but I'm sure they still do use Lard in the Taco bell beans.