But the next phase for his Joker would have to be to see him shed his nervousness and for intelligence to come to the fore.
Maybe he can start taking his own medicine -- a super cocktail of psychotropic drugs to enhance his "intellect".
There's ways to do it. BUT...
I doubt Phoenix or Phillips would ever want to bring their Joker down to the super-villain comic book level you guys want so much. This is just a different universe.
Here, even Batman wouldn't be the Batman you guys want. He'd probably be an actual detective more than a superhero, and his Bat-attire would likely be a scary costume more than impermeable armor with tons of all-purpose gadgets.