The Send JSON Path syntax for accessing an element from an Integration Procedure structure is BlockName.ElementName. In this case, the BlockName is BlockX and the ElementName is ActionZ. The colon (:) is used to separate the input and output parameters, not the block and element names. The order of the block and element names should follow the hierarchy of the structure, from top to bottom. The Additional input parameter is not needed in this case, as it is already included in the Send JSON Path.

According to the Troubleshoot Flow Errors page, one way to troubleshoot errors is to "check the debug logs for the community". Another way is to use the Action Debugger tool, which "lets you test and debug actions in OmniStudio".

The merge code syntax for accessing a node from an Integration Procedure output is {{ProcedureName:
NodeName}}. In this case, the ProcedureName is HTTPGetCaseDetails and the NodeName is CaseData. The
% sign is used for single-value merge codes, not node merge codes. The $ sign is used for variables, not merge codes.

The Use Data JSON property must be selected in the properties of the Type Ahead Block in order to display the fetched data in the fields. The Lookup Mode property is used to specify the type of lookup to perform. The FirstName, LastName, and BirthDate fields can be placed inside or outside the Type Ahead Block. The typeHead key is in the correct format.

According to the Integration Procedure Actions page, a Calculation Action can be used to "call a Calculation Procedure that performs calculations on input data" and a Matrix Action can be used to "call a Calculation Matrix that performs calculations on input data".