I'm afraid that EL didn't exist last time I did
JSP editing in Emacs. Back then I was struggling with getting it to handle scriptlets properly.
I solved the scriptlet problem. I learned not to put logic on my web pages. So no scriptlets.
If you're proficient in ELISP, you might want to dig out the stuff that highlights shell script variables when editing in shell mode. The same general rules for highlighing "${VARIABLE}" expressions should be adaptable to "#{el expressions}".
Unless you're doing free-form EL on a webpage, however, you'll probably have your EL in quotes, and the quote highlighter would normally be given precedence. At that level, even heavyweight IDEs like Eclipse only do a so-so job.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.