Yeah if you’re runnin’ distilled water at 0 PPM, you def gotta be adding Cal-Mag, even if you're using Sensi Coco.
Sensi Coco’s got a bit in it, but not enough when your base water’s straight-up empty. Coco coir loves to suck up calcium and magnesium, so if you don’t feed extra, your plants will start showin’ issues real quick especially with autos that don’t give you much room for mistakes.
I’d start with 0.5 to 1 ml/L Cal-Mag, just to bring your base up to like 150–200 PPM before you mix the rest of your nutes. Keep that steady in every feed.
Rest of your setup looks dialed, and runnin’ AN with Fast Buds is a solid combo. Just don’t sleep on that Cal-Mag and you’ll be smooth sailin’ ✌️🌱💨