Thanks for the offer. I appreciate it. Here is what I've been able to learn about dbl.el and sshell.el from looking at git history and from the maxima mailing list.
First, these were written by William F. Schelter around 1998 at a time when GNU Emacs was very different. He unfortunately has passed away and no one has been maintaining the code.
The current state of the art for LISP debugging in Emacs is SLIME (Superior Lisp Interaction Mode in Emacs) and that is in active development.
Realgud is simply a front-end for various debuggers like gdb, pdb, perldb. Think of it as a replacement for gud which is where it derives its name.
realgud also supports some more exotic debuggers like the debuggers for GNU make, bash and zsh. The project is located at
https://github.com/realgud and you can install it from either ELPA and the official Emacs lisp package repository, or via MELPA for newer versions. The list of debugger it covers is
https://github.com/realgud/realgud/wiki/Debuggers-Supported
As best as I can tell, no one is using dbl.el or sshell.el and the code is duplicated with code from maxima. Given this and its unmaintained state, my recommendation is to remove these altogether as they are enticing users to go down a road that may be fraught with problems and cause them to contemplate improving code that would be better spent on one of the better packages.
So if there are features that people use in either of them, let them speak up here and we can consider adding them to some other currently-maintained Emacs package.