The vision cones need to be at least 180 degrees to account for peripheral vision and simply turning your head.
But then, as mentioned many times before, when you account for hearing and smell they should really be using a detection radius instead. If they want to gamify stealth, they could make your Perception rank increase the possible detection radius. Like 15m + Perception modifier. I would get rid of the cones entirely and use a radius instead. If they insist on keeping their flawed cones, they need to add a hearing radius on top of it. And then the whole thing will just be needlessly complicated.
Abusing some narrow gamey cones in turn based mode to "sneak" with your -1 Stealth Disadvantage PC while enemies are frozen in time is not fun gameplay. And it takes away from actually stealthy builds. Larian need to stop overriding D&D mechanics with their silly gamey inventions.
And cut back on the abundance of Invisibility potions, please. A character in medium or heavy armor with Stealth disadvantage would still make noise while invisible and should be easily detectable. Stealth disadvantage should be meaningful. It's one reason to wear a Breastplate or invest in the Medium Armor Master feat. Surprising enemies and getting surprised on a high Perception character are both too easy.
