I mean I’m not the dictator of best practices but I am certainly well opinionated on the topic (almost any topic
just ask @jgiese.wci and @Banderson ).
I would say if you can avoid making BO calls on AppStudio then do.
Get into them, they are the best thing that Epicor has given us in years.
I will almost never make BO calls in App Studio. Move all your calls to functions and BPMs, move all your logic to the back end. I just posted this on another topic but frankly it applies for this too so I won’t repeat myself I’ll point you in that direction instead