Can we make the comparison optional?  It would be useful to have a rule that doesn't look for a exact match, just that it failed.  You might also consider making compare-value a list and use lists:member so one rule could represent several failure conditions.

I expect the most common use case will be to simple reschedule a fax for 30 minutes from now if it fails, regardless of why. 

side note: on multi-line case clauses like this we would typically dropline the 'of'