Old thread, same problem. This was the solution that worked for me.
Of interest, I could not use an input parameter of the same name in the parent CV as I was using the child CV. In your example you were able to use the same input paramter names.
For example, I had the two CV's, each had an input parameter ACCOUNT.
---This did not work, kept getting syntax errors no matter what I did
table =
SELECT COLUMNS
FROM "_SYS_BIC"."CHILD_CV"
(PLACEHOLDER."$$ACCOUNT$$"=>:ACCOUNT)
---This worked, changed the parent/calling CV input parameter name
table =
SELECT COLUMNS
FROM "_SYS_BIC"."CHILD_CV"
(PLACEHOLDER."$$ACCOUNT$$"=>:IN_ACCOUNT)
This was tested on a revision 82 box.