Sorry for the delay in replying..
It sounds like you are doing things right with the exec_ssh regex, and that should work passing both arguments.
The tricky part is how you are using the script_lib dosearch using the + thing.. That is getting a little advanced..
I wonder if you could solve it like this:
In the script_lib alias result, do a setuservar command to save the value of $$2 to a temporary variable like "uservar.temp.sshvar2", and then create a new exec_ssh replacement alias that only expects $$1 and then uses "%uservar.temp.sshvar2%" instead of $$2.