How do I figure out the right pronunciation for transitions? For example, the CNERY transition,* how exactly is this pronounced? On the VATSIM community, it seems there's a huge debate on what this is called. Some people say CONNERY, and some people say SCENERY. I personally say SCENERY since it makes more sense, but what is the most proper one? And is there a place where we can find pronunciation of such things?

Like another one is SCTRR transition which some people say SCOOTER, some people say SCATTER.

* CNERY transition is part of KLAX's DOTSS TWO DEPARTURE.
It would be nice if there were an authoritative, canonical, source for these sorts of waypoints, but sadly, I don't think one exists. I say that because I hear controllers sometimes using a different set of vowels or syllable emphasis "today" than they did "yesterday". If there were a single "right" way to verbalize CNERY or SCTRR, I'd expect ATC to have them all down. But in plenty of cases beyond those two, it remains unclear. 

For example, the JFRYE arrival into Dallas -- is it the "Jeffrey" or the "J-Fry" arrival? You hear both from Ft Worth Center all the time.

My conclusion: no cannonical source exists.