I wonder if Venusians tried the same thing which lead to the concentrations of SO2 we see in Venus' atmosphere.

As long as so many coal plants are happily smoking and even more are about to be build, I think the first priority is to shut them down and replace those, instead of experimenting with the already quite instable global climate, by injecting more chemicals.

And after we stop emmitting CO2, we can focus on artificial decarbonization. But I would rather invest in proven technology, like reforesting first.

I read something recently about seeding beaches with crushed limestone which accelerates CO2 absorption through weathering or something.

I think that was what the movie Snowpiercer was about. It ended badly before the start of the movie, with an ice age.