I suppose that in GOA increasing the bias has only effect on odds calculation of combat.
I'm trying to recall if the AI gains a "cheat" benefit in combat when the handicap is on. It may, I'd have to go back and look. However, off the top of my head I believe the only AI advantage is 50% more economic points. Since the AI will never spend as wisely as the human player I don't see this as being much of an advantage myself, more of an "evening up".
as Russians in the east still were slow in exploiting the weakness of CP
The Russians have a very long front and as the AI thinks defence first they will move slowly when on the offensive because they just don't do as well as a human at allocating troops and HQs so as to free up a reserve for offensive purposes.
I wonder whether, through some diffrent programming, AI could be made to somewhat replicate in East Prusia-Galicia, Serbia and Turkey (as well as in the Salonika area too!) the aggressive conduct of operations it regularly displays on the Italian Front
It is probably possible to increase aggressiveness.