According to the documentation, there is a parameter "pFormat" that has default value acelo, where:

• c - output the ObjectScript-specific "_class" and "_id" properties

So, if you just call the transform like this, it should work:

set dynObj = ##class(%ZEN.Auxiliary.altJSONProvider).%ObjectToAET(person, , , "aelo")

After executing your query, you need to move cursor and then you can get data:

SET SC = resultset.Prepare(sql) 
SET SC = resultset.Execute()
if (resultset.Next(.SC)) {
	quit:$$$ISERR(SC)
	set cnt = resultset.Data("CNT")
}
SET SC = resultset.Close()