@SotiCoto The only explanation I can think of as to why Americans tend to say "erb" is because historically speaking, like waaay back in the 1300s when this word became a thing in English, herb was originally not pronounced with the H. British people eventually were like "uhh there's an h, so we're gonna actually pronounce it," but as you've mentioned, Americans now for some reason go back to the old Latin and sort-of-French way of saying herb. Not sure why--language is just weird like that!
Also, I was technically wrong in my first comment. I'm an American myself and somehow didn't realize until now that most other Americans (besides me, apparently) actually pronounce the h in "herbivore." The only h we don't pronounce is in the word "herb." So you were absolutely right! And sorry for misleading you. The translator definitely should have put "a herbivore," as it would be 100% correct in both American and British English.
We have a really weird and I assume irritating way of pronouncing certain things I guess, haha. Like, I spelled "arctic" like "artic" up until around 6th grade because most Americans pronounce it like that (mostly because some of our accents don't allow us to smoothly pronounce the "c" in arctic, and I believe it's the original English/French pronunciation as well)