Does "estoy en ello" translate to English "I'm on it"? That's a colloquial, informal expression in English. Is it also a colloquial, informal expression in Spanish? Such a coincidence. What's the history of this expression?
English and Spanish have a shared ancestry if you go back two thousand years. Is "estoy en ello" an example of that? Or did Spanish pick up this expression from American movies in the last 20 years? Or vice versa. Perhaps there will be no answers. But it is interesting.