If lestat is a co-founder of the Paris theatre and a powerful vampire, couldn’t he persuade the others to stop the trial?
The thing is... the version of the trial we'll probably see at first... is not how it went in the books. IDK if we'll get to see the version which is more in line with the books, BUT in any case - the big tragedy of it all is that Louis and Claudia literally killed off their one protection (and, though they didn't really kill him they weakened him a lot).
Lestat, powerful or not, is no match for a whole coven and Armand.