>> I'm going to assume this project is at best a few years old, so return over index is more likely to be an indicator of overbetting (taking on too much risk) than a performance indicator.

Best metric here would be a Sharpe Ratio and drawdown details. https://en.wikipedia.org/wiki/Sharpe_ratio

> This system is impossible to test. I would be hesitant to trust it.

Disagree. Best test would be a paper test going forward, audited by a common platform.