Humans have already measurably changed the angular velocity of the Earth with dams. Not sure why you think it will never be possible to change angular momentum, you just need minor planet collisions and/or flywheels.
The Chicxulub impact is estimated at 10^24-10^25 joules. So we need 10k-100k Chicxulub impacts in such a way that the energy is perfectly translated into Venus’s rotational energy.
That’s what, a billion tons of antimatter-matter reacting?
I don’t think we’re going to have a 24 hour day on Venus anytime soon.