I dont believe it’s difficult but the problem is the use of xml and soap. Your developers probably want rest and JSON?
My preferred approach would be to use java or c# to communicate with the gateway (they have more extensive libraries for dealing with XML and soap). Then transform this into rest+json, probably using FHIR as the api data model will probably match FHIR (from memory it does do).
I’d probably go with java as open source support is more comprehensive - I’m using apache camel and HAPI fhir to do something similar at the mo.
I may be able to help with the development but would need a java/c# developer to do the actual coding.