"Está lloviendo mucho."
Translation:It's raining a lot.
It's raining hard is colloquial and not an everyday worldwide expression.
In my experience, "It's raining hard." is probably the most common way to say this phrase in English.
"It's raining cats and dogs." may be a close second!
But did any of you report it? DL accepts lots of alternative translations. But they don't read this forum ... they react to exercise reports. I've received five acceptance emails this month alone. If you think your answer is correct, report it. Just one click is all it takes ... much easier than writing a complaint here.
Do you not think that It's raining lots is colloquial (and equally not an everyday expression)?