I am sorry, but I'm not sure to understand and I would like to have some precisions.
In the medieval times there where 3 considerations for succession law :
1. A male preference succession law where females should inherit when there is no more males. This is the most common succession law in the medieval era but wasn't implemented in CK1. This succession law is commonly named cognatic.
2. What CK1 named "semi-salic" which is the Plantagenêt interpretation of the salic law : only males can inherits, but female could grant to their sons rights to inherits. You say that the cognatic law of CK2 is "semi-salic".
3. What CK1 named salic which is the Valois interpretation of the salic law : only males can inherits, only males can grant to their sons rights to inherits.
Does the "cognatic law of CK2" si for the 1st or the 2nd case ?
Thanks in advance.
Cognatic as implemented means that females may inherit in the absence of eligible males. I suppose it should actually be called Agnatic-Cognatic Succession.