Something in the most recent patch fixed this issue.

This is no longer happening.

An easy way to avoid the problem of sights becoming inaccurate when changing your fov would be to make two separate fov settings, one for your normal view and one for your scoped view. You could change your normal view fov, but when scoped in you would always have the same fov (it would zoom your view in the same amount when scoped in regardless of your normal fov.)

I don't think they should slow down the throwing animation, because that would take a lot of control out of the player's hands. It would make the throwing of the grenade feel disconnected from the player's actions. You would have to hold your point of aim in one spot through the whole animation.

But one way to solve this is by requiring the player to perform two actions, the first would be prepping the grenade to be thrown (getting it off your gear and into your hand, ready to pull the pin and throw), and the second being the actual pin pulling and throwing. This way the player would still retain control over the precise moment the grenade is thrown, while increasing the realism.