Such rumors are commonly heard these days.
I converted this as:
We hear these rumors commonly these days.
Is it the correct active form?
Your suggestion is valid, but would mark you as not being a native speaker of English. Idiomatic English normally places the adverb close to the verb it modifies, so "We commonly hear such rumors these days." would be a better formulation. Another alternative, perceived as more formal (or perhaps more British, as opposed to more American), might be to use the indefinite subject one: One commonly hears such rumors these days.