Other people addressed the specifics but to add more generally, the key question is almost always not “can we do it”. It is almost always “can we do this more economically than other methods” and the answer is no. It takes more time, money, resources, etc. for a given amount of power than other clean energy technologies.
It is not very likely that there are tech improvements that would make things like this more viable. Salt water is super hard on equipment and that will always be true. Any improvements in durability would likely also apply to wind components. Gravity is only powerful at large scales, so just using tidal forces means you have to harness a lot of water, which means use land use and environmental disruption. Water batteries are economical only in places with extremely specific geography.
It is not very likely that there are tech improvements that would make things like this more viable. Salt water is super hard on equipment and that will always be true. Any improvements in durability would likely also apply to wind components. Gravity is only powerful at large scales, so just using tidal forces means you have to harness a lot of water, which means use land use and environmental disruption. Water batteries are economical only in places with extremely specific geography.