So far, Artificer is the only RoR2 character, who has cooldown on primary attack ability. This makes my wondering, how attack speed improve Artificer capabilites. Does it decrease cooldown?
No, attack speed will not lower the cooldown. Attack speed will increase the rate at which the bolts are fired once they are charged. However, to increase the rate at which the bolts charge, you'll need something like an Alien Head to decrease the cooldown.
If you only build Soldier's Syringes on Artificer, your rate of fire of the primary ability will still be hard capped by the cooldown.