Tim, sgs.prasad is correct... transaction type CST-ADJ is the result of manually changing the GL cost, rolling the cost directly on the GL cost set or after doing a cost-set to cost set copy.
Not clear on what you mean by "want to verify that we have to create a journal entry to affect the GL".
If the inventory account is out of balance with the inventory valuation there are other issues... any change in qty or cost (or any other type of transaction) should be correctly reflected in GL and match the InvValue. Check GL for non inventory related transactions; the most common cause of unbalance, aside delete or change of transactions.... if this happens a lot, check if there inventory account is used somewhere else in the setup of product lines.
and no... sct_det SHOULD NOT be modified directly... just in case.