Both tonality and Soundstage mostly have to do with frequency response relative to your ear-anatomy.

Frequency response = volume of each frequency on the spectrum, when measured, forming a curve that indicates a certain sound profile.

Tonality = overall balance.

Timbre = how smooth and consistent the tonality is because if it deviates a lot, if there are significant peaks or dips in several places it will mess with everything, though my experience is that it's a bit different on headphones as opposed to in-ears.

Sound stage = really just a blanket term for treble extension and good tonal balance. In other words, right amount of lows, mids and highs.

Fun to play around with once you get familiar with EQ.