Ah, yes. This is an interesting challenge. Janino creates Java code and we only need this feature if dynamic changes per request are required but on mobile we probably only need server side support?
And for server side custom weightings we could create Java code via Janino while the CH preparation (or import) or Objective-C conversion (there is a debug feature which emits the code - see CustomModelParser.JANINO_DEBUG and SCRIPT_FILE_DIR).
So could it make sense to replace this dependency with some static code like we replaced MMAPDataAccess?