If boom mics are worn and designed to stay on during severe turbulance! they remain the best solution.
The overhead mounted ambient mics with an omnidirectional pickup pattern cant be expected to recieve the pilots voice clearly when pilot is looking at instruments and when the warning speakers are direct line of sight to the mic.
A couple of panel mounted directional mics each aimed directly at where the pilot and FO is looking could be considered if boom mics cant be relied upon.
This will reduce background level relative to voice level. These mics and the ambient mic could be fitted with wind gags to eliminate the sound of air moving over the surface of the mic, so called "wind noise" that would otherwise greatly reduce the fidelity of the recording during a decompression or other event.
Cameras that show the crew mouths will help with deciphering what was spoken.
I guess that cvr use compression? Use of high rates of compression when there is lack of control over mic placement and background sound and when level control is "auto" is to be avoided. Compression trys to keep every hum and background noise (there is considerable background noise of air over the fuselage) at the expense of reducing amount of data to record the good stuff.
As with images, the less control of the subject the more beneficial it is to have a high fidelity equipment, in this case microphones and a recording strategy which allows far more detail to be extracted post event.
A camera looking into passenger cabin would be very useful to evaluate passenger response to emergencies including evacuation.