It is often difficult to interpret the meaning of MIRIAM-compliant URNs. The MIRIAM project provides a special XML file that allows translating a MIRIAM URN into a list of existing URL. It would be nice if JSBML could offer a function that simply returns all actual URLs for each URN within a MIRIAM annotation of some element.
You have already a miriam web service that can do that for you. We could try to write a small module that is doing the job using the web service in fact. The miriam tools developers are also planning to release a version of their library that would be only local, using the xml file so we could use this one or offer the possibility to use the web service or the local one, when it is available.
see http://www.ebi.ac.uk/miriam/main/mdb?section=ws
On a separate project, we did develop a local library that allow to do all of that and all of what the miriam web services are providing.
See https://sourceforge.net/p/identifiers-org/code/HEAD/tree/registry-lib/