Let's be clear about something. When Phoenix was stated as being the same energies that ignited the big bang that does not make her creation itself...
Invisible women can harm celestials because ironically her powers consist of Te same as theirs...
Living tribunal steps in when an abstract asks or he feels the multimeter is in danger as a whole...
During the infinity saga he was asked to empower the infinity gauntlet etc..
Korvac threatened to exceed his realm...
The chaos wave had greater influence due to extenuating circumstances and was not the scarlet witches actions alone...
It also did not endanger the greater universe but only changed it... Same as the Jean grey feat... Scarlet witch said no more mutants... Jean said Scott go hook up with emma...
And his not havinge to act during the mkrann can just as easily mean the multiverse was never in peril.... He is omniscient after all... Or a real deal of monkey pis...
Take your pic. Differences of opinions that's what we have. :-)