Feature phone operating systems are generally proprietary and are developed in-house by the manufacturer. So we'd have to put something vague like "LG proprietary OS", or Samsung OS. There often is no public name for the operating system. If there is a name, say the Moto phones that run Linux variants, we state it. Smartphones always have a branded and disclosed OS, so you'll always find that info in our specs section and in the body of the review.
When the manufacturer (or a testing utility) tells us what CPU a phone has, we state it in the specs, likewise for RAM. If they will not state this info and there's no utility to find out, then we have to leave those specs out. So if it's not there, take it to indicate it's unknown .