Prior to version 2 of the plugin, the JCL that was submitted allowed for variable substitution within the job.  We used this extensively (generating timestamps, starting/stopping configurable CICS regions, etc) in the JCL that we have and were running on a regular basis.

I can't think of a simple way to replicate this.  The best I can think of is an intermediate step from checkout to injection where a shell or command script is run to perform the substitutions prior to the submission.  But this feels a bit awkward, and error prone.

I'd really like to see this functionality restored, if possible.

Happy to look into it myself, just might take a while.