Veigar still overnerfed
I'm very glad he was reworked, and that there is much more skill involved on both sides now. However, lowering his mana costs and buffing his Q range was not nearly enough to compensate for the extreme nerfs to his stun and ultimate. He's at a 47% winrate. You said in your patch notes "you can't reduce a 100-0 burst mage to 100-20" but that's what you did by lowering his ult's AP ratio by 20%.
If you want to add more counterplay, increase the enemy's AP ratio by 20% (so they are both 100%). The enemy can counter this by not rushing Rabadon's. This also curbs snowballing on both sides, since Veigar's burst will be partially based on how fed the enemy mage is.