[I wrote this several days ago and it dropped through the cracks of the email system. Nevertheless, I think it still needs to be said.]
As an independent consultant who uses various rulebased systems, some are called Business Rule Management Systems, or BRMS, I think I'll have to somewhat agree with Ernest in that each rulebase has its own, individual features and benefits, handicaps and drawbacks. For system that is free for academic or government use, although it does cost quite a bit for commercial use, Jess is one of the best there is. In my humble opinion. Especially considering the support that you get with Ernest et cie.
Now, just in case you missed an earlier email, trying to write a parser to translate code from one system to another is madness of the first magnitude. Each system has things that the other one does not have. And each system has a different "way" to code things. Jess has a limited form of backward chaining. The old Nexpert (Neuron Data Expert now owned, but not promoted, by Fair Isaac) was a true, fullly opportunistic backward chaining system. Mandarex is a backward chaining system only. Blaze Advisor has a "when needed' clause that can be used to simulate backward chaining. OPSJ, at one time, incorporated backward chaining elements that were later taken out. As one a God Father of the industry once said, "Any forward chaining engine can be made to do backward chaining and any backward chaining engine must eventually forward chain to deliver results."
So, please, please, please do NOT do what you are suggesting. Stop. Learn the language. Learn the benefits. READ THE FABULOUS MANUAL and the book!! Get familiar with what you have with Jess. THEN do something constructive with it. THEN you will understand why we (everyone who has written on this mailing list on this subject) keep saying, "Don't do that!"