The treble looks fairly elevated & intense(the reason I avoided these):

Graphs can only roughly explain what is really happening during listening.
I don't find the treble fatiguing, bright or harsh.
It has plenty of energy and air, it is luminous but in no way intrusive and intensive.
Of course you might be more sensitive than I am to this region but you should remember that I don't like bright, unforgiving and analytical stuff and the S12 PRO is not.

3 to 5 kHz is the critical region and as the graph suggests it is well tuned.
The brilliance range is composed entirely of harmonics and is responsible for sparkle and air of a sound.
It is boosted here but it mainly adds some kind of a metallic - artificial hue to the treble that being fatiguing.

If you are too sensitive you should give the P1 MAX a try instead of the S12 PRO.

Do you think they're live stage suitable as a musician IEM? Especially for drums? Thanks

@MartyPorkSoda
Hi, I am not sure what are the criteria that must be met in order to be used for live staging and drums.

Natural balanced sound with good instrument separation and sound stage and also good isolation Fast and accurate bass response for kick drum and strong mid range for guitars clarity. Ideally.