The concept of using a novel financial system is not flawed, but I should hope the financial system is, because that gives you plenty of scope to create your story. Most systems are flawed to a greater or lesser degree, and if they are not, humans will soon find a way to corrupt them. Really interesting to see how your aliens view/value/manage a human financial system.

In scifi or fantasy or scifi/fantasy, you can generally get away with one big fictitious element. So currency as an idea doesn’t actually have to work, as long as everyone in the novel believes it works (I’m not actually sure, in this case, how that differs from the real-world money markets or the 2007/8 financial crash, but let’s not go there for the moment). So in a novel about airships, the fictitious idea is that airships actually work as a general means of transport.

Once your readers have accepted that one big fictitious idea, everything else needs to be workable.

Whilst the financial system is not the story, the pros and cons, or advantages and disadvantages/injustices of the system will drive how your characters react, what they value, and the choices they make.

One of my favourite films is the brilliant, In Time, with Justin Timberlake, there the currency is ‘seconds-of-remaining-life.’   In this story, the length of your life is literally linked to what you earn and spend. Whilst the story is not about the financial system itself, it still controls every action/decision of every character, literally down to the last second.

Nick