AFAIK No. There is no straightforward way to import JSON from FHIR discrete resources to SDA3 objects by %JSONImport(). Basically, there are various stages involved in converting the FHIR to HL7 and vice versa. To achieve this, Intersystems created an intermediary format called SDA. However, there are more processes involved whenever convert the bundle or discrete resource.
for example

1. In some instances, the FHIR resource data element name (property) is not the same as the SDA property.
2. Lots of internal DTL's are invoked or invoked at the conversion time, and an SDA object is created based on that output. Typically it's common for SDA to FHIR and vice versa. 
3. DTL's are crucial to accomplish this conversion. Some of the data elements are not mapped in the standard FHIR to SDA or SDA to FHIR DTL transformation. HS.FHIR.DTL.vR4.SDA3.AllergyIntolerance.Allergy in this DTL the "criticality" data element is not mapped with SDA object In this case you should create your custom DTL from the already implemented DTL to convert the values to object. So If you haven't added this type of additional properties in the SDA extension class, it won't work.
4. Metadata values and lookup tables vary from SDA to FHIR. SDA has 'A' in the lookup tables for some fields, while FHIR has 'Active'. There is a internal validation runs against every data element to verify the generated FHIR resource Every time

The reason behind the conversion is Cache identifies/assume from 1900 - 1999 year if you send two digit for year. So, You should send four digit year. attached the documentation "Two or four digits may be specified for years in the range 1900 to 1999. Four digits must be specified for years before 1900 or after 1999."

As per your code. Couple of things. Firstly, the item is list of object so you should use Insert method. You're inserting item.ItemName instead item object. Property Item As list Of AllItems; expects object. Not a string.

I'm not sure why the request class CSVtoHL7.Inputfile.Record inherits from right. All the request and response are required persistent object. This will be used to display the entire flow in the visual trace section. I have attached some sample below.

You can add a property setter method for property DOB and modify the value from MM/DD/YYYY to +$H value. This will keep the internal date format in database.

Class CSVtoHL7.Inputfile.Record Extends (Ens.Request, %XML.Adaptor, EnsLib.RecordMap.Base) [ ProcedureBlock ]
{
Property ID As %Integer;
Property LastName As %String;
Property FirstName As %String;
Property MiddleName As %String;
Property DOB As %Date;
Method DOBSet(pDate) As %Status
{
    Set i%DOB= $ZDH(pDate)
    Quit $$$OK
}
Property Gender As %String;
ClassMethod createObj() As CSVtoHL7.Inputfile.Record
{
    Set obj = ##class(CSVtoHL7.Inputfile.Record).%New()
    Set obj.DOB="12/30/2001"
    Set obj.FirstName="Test"
    Set obj.ID=12345
    Set obj.MiddleName = "middle"
    Set obj.Gender="M"
    return obj
}
}

Create a object for the request class and send to Transformation. you can use the logic $translate($ZDT(source.DOB_",0",3)," ","T")_"Z" in DTL to convert the internal date format to required output 2023-08-24T00:00:00Z. You can refer the DTL sample below

Class CSVtoHL7.DTL.Record Extends Ens.DataTransformDTL [ DependsOn = (CSVtoHL7.Inputfile.Record, EnsLib.HL7.Message) ]
{

Parameter IGNOREMISSINGSOURCE = 1;

Parameter REPORTERRORS = 1;

Parameter TREATEMPTYREPEATINGFIELDASNULL = 0;

XData DTL [ XMLNamespace = "http://www.intersystems.com/dtl" ]
{
<transform sourceClass='CSVtoHL7.Inputfile.Record' targetClass='EnsLib.HL7.Message' targetDocType='2.5:ADT_A01' create='new' language='objectscript' >
<assign value='source.ID' property='target.{PID:SetIDPID}' action='set' />
<assign value='source.FirstName' property='target.{PID:PatientName().FamilyName}' action='set' />
<assign value='source.MiddleName' property='target.{PID:PatientName().GivenName}' action='set' />
<assign value='source.Gender' property='target.{PID:AdministrativeSex}' action='set' />
<assign value='$translate($ZDT(source.DOB_",0",3)," ","T")_"Z"' property='target.{PID:DateTimeofBirth.Time}' action='set' />
</transform>
}

}

output

As we mentioned above the DOB should have +$H value instead of MM/DD/YYYY. However you can try the below

If DOB is date format

IRISMYDEV>set dob="12/01/1993"
IRISMYDEV>write $translate($ZDT($ZDTH(dob),3)," ","T")_"Z"
1993-12-01T00:00:00Z

If DOB is +$H value

IRISMYDEV>set dob=+$H
IRISMYDEV>write $translate($ZDT(d_",00000",3)," ","T")_"Z"
2023-08-24T00:00:00Z

Hello Smythe,

I agree with @Robert Cemper points. The %Date datatype is for +$H which means numeric date value. Not an string. You should modify the datatype of the property or use string functions.

IRISMYDEV>s obj = ##Class(CSVtoHL7.Inputfile.Record).%New()
IRISMYDEV>s obj.DOB="12/12/1993"
IRISMYDEV>zw ##Class(%Date).IsValid(obj.DOB)
"0 "_$lb($lb(7207,"12/12/1993",,,,,,,,$lb(,"IRISMYDEV",$lb("e^IsValid+1^%Library.Date.1^1","e^^^0"))))/* ERROR #7207: Datatype value '12/12/1993' is not a valid number */
 
IRISMYDEV>w $SYSTEM.OBJ.DisplayError()
ERROR #7207: Datatype value '12/12/1993' is not a valid number1

IRISMYDEV>s obj = ##Class(CSVtoHL7.Inputfile.Record).%New()
IRISMYDEV>s obj.DOB=$ZDateH("12/12/1993")
IRISMYDEV>zw ##Class(%Date).IsValid(obj.DOB)
1

Hello Pierre,

No problem. You can use the merge command(sorry not a string function) to take a copy of entire global node and subtree

merge queryparam = %request.Data
zwrite queryparam ;print the entire node and subtree