if the charity only needs an appropriate return to invest in such projects, and the bank provided that, it's a good transaction for the charity, which fulfills all its goals, and a good one for the bank which can make money in the process.

Presumably the charity can consult several banks to see which one offers the best overall package?

What is trickier is if the proposed structures end up putting other risks on the charity than what it expected to bear, or that the structure is sold as something it isn't (as happened with whole classes of the "structured products" of recent years).

In the long run, we're all dead. John Maynard Keynes