I used RR in the past, pretty stable for me but didn't used voicecall on whatsapp unfortunately.No, I didn't install another one before on this phone, i was told that this one should be the most stable for this device and I gave it a go.
Maybe LOS 14.1 is the next in line if I'm searching for stability or is any other you recommend to use instead (despite I've rad that in latest LOS 14.1 there are a few problems with battery drainage while in standby without solution too)? I'm sorry to ask for another ROM in this thread but at this moment is the only "solution" available to solve this issue when using the combination Samsung SM-J320 + RR 5.8.5.
If you want give los14.1 a try. No bugs so far, even the flickering is fixed. You can make a backup of current RR in twrp and if LOS14.1 doesn't work well restore the backup.