I think there's a degree of agency implied in that English use; most things can't do things themselves in English. Compare 'The computer reboots itself' or 'the oven cleans itself', both of which have specific agency, or 'the bottle seemed to empty itself', where the inability of things to act is used to make a point.
The normal English here would be 'The room clears' I think.
A guide I have found useful in understanding these Italian constructs, is that if the "action" of a verb occurs to the thing doing the action described by the verb, then the Italian is normally constructed with a reflexive form of the verb. In English, the reflexive pronoun is not normally translated in these circumstances. eg The car stops = La macchina si ferma. Purely a difference of linguistic constructs.
In comparison, consider "He stops the car", He is causing the stopping but the action of stopping is done by/to the car so it is not reflexive. Lui ferma la macchina.
I hope that makes some sense. I'm rather grammatically challenged and find it hard to explain clearly.
Translation in the target language should not be word for word. It should fit the structure and normal usage of the target language. In this instance, the English translation provided is not normal English. There are several other translations provided below that would make more sense, I think. The moderators should look into using one of them, instead.