My opinion based on past fish in my 4' 75g;
Aside from your bioload in a 30g, the established clowns will fight with the angel as it cruises through their territory, if they haven't already claimed the whole tank.
Then any dwarf angel will attempt to claim the whole tank for
themselves.
And neither fish will back down from a fight.
I have a 2" coral beauty in my current 75g and it tries to fight with my 3-1/2" yellow tang, and chases my springer's dottyback.
Not the most peaceful fish, and a flame would be just as aggressive. They need a large grazing area.
You didn't mention what cardinals you have. My PJs kept away from other fish but disliked each other. My Bangaii turned into a territorial turd and was evicted.
Regardless, my personal preference is to keep no more than 1 fish per 5 gallons.
I had at one time 15 fish and there was a constant pecking order battle.
I prefer a more peaceful tank and have resigned myself to keeping the tennant's
#s under 10 now, with a varied mix of species to best avoid fighting/stress.