Does it make sense to use Google advertising?
Of course it does. After the ban removal for crypto ads though its only for specific advertisement still its one of the best type of advertisement to any project.
Do you believe in the effectiveness of bounty programs?
I do, you reward them with the allocated budget to help you with the promotion. But if the effectiveness becomes low, I might stop it and conduct other way of advertisement.
What do you mean by another type of advertising? How legal will it be to stop the bounty program? This is likely to be a serious damage to the reputation of the project.