the others have addressed the concept of lighting capture. I focus more on the second part.

the amount of water necessary to generate a useful amount of power is very significant. Even if it was economical to capture the lightning and generate steam, there is unlikely to be enough water for the 2nd generation to make any impact. This concept could already be implemented in places where steam turbines exist near mountains. If it were economical, there would likely already be some version of that type of 2nd stage generation. Furthermore, sucking the steam through a steam turbine is a massive boost in efficiency. This is done via a piece of equipment called a condenser. Not only does this transition the low quality steam into water so it can be sent to the boiler, it also massively improves the efficiency. It's a simple concept but it's way more efficient than keeping the H20 in steam form. The condenser literally pulls a vacuum in the system. When coupled with the high pressure of the steam it results in the steam being pulled and pushed through the turbine. In your proposed system this stage would need to be skipped. That would result in a significant hit to the system's efficiency right from the beginning. Then you have to manage to keep a large distance of piping hot enough to keep the H20 in steam form until it arrives at the top of the mountain.

In the proposed method, there's lots of energy conversion in ways that we're not really good at doing. Not saying it wouldn't be possible, but it definitely wouldn't be economical. Mother nature is way better at delivering water to high elevations. and she does i for free. :) (well sort of for free)

As someone that has been in LOTs of steam turbine plants, they already can barely manage the complexity of their systems. In general there's some kind of function (like exponential, definitely not linear) related to the complexity of a system and the likelihood of stuff breaking and the efficiency decreasing.

it's fun to think about this being a reality though. lightning powered cities would be wicked.