I created a simpler (more likely to get implemented) feature request for this you can vote on: https://answers.presonus.com/46228/add-ability-to-fade-audio-parts-like-events
They’re not buggy, just not setup the way you want
Also if you turn off snap to grid with N then bouncing will not require additional trimming as you mentioned.
I’d love for them to put in fading merged events but until then it sounds like you could benefit from taking a second look at the way the current tools are setup:
From a Support tutorial:
You cannot just grab a fade handle on an Audio Part to fade clips inside of it. You would instead double click the Audio Part and perform those edits in the editor. However, the actions "Fade in To Cursor" and "Fade Out From Cursor" (they are unbound by default so if you want to use them go to the Keyboard Shortcuts editor and bind them to keys) will work on audio parts for that.
also, you can Select an audio part and hit Shift+X to create small auto-fades on all the clips in the audio part.