Here's the minimal repro steps in order to exchange files with AIF file adapter over Counting journal services. In the end, we will have a new journal with one line. This was tested in AX 2012 R2:

1) have a standard item without configuration
2) Configured an inventory counting journal in inventory parameters on AIF tab
3) Have visual studio in place to check schemas
4) Configure a file adapter inbound port for service InventCountingJournalService that exposes the create method. Constraint the file adapter to a partition and a company
5) On the service inbound, customize data policies and enable both inventorySiteId (inventJournalTrans and inventJournalTable) fields

1) Get the XSD from the services and it's shared types by exporting them over the Data policies, view schema on the service
2) Open visual studio and load the XSD
3) On the root node of the XSD file right click on it and select "generate sample xml"
4) Over the sample XML, change the XML accordingly (only the create action)to reflect the data we want to create
5) Remove create action for the entity classes
6) Fill itemId, InventSiteId tags
7) Save the finalized XML inside the folder AIF is listening to

In the end you will have the following XML: