> Would you say that a misuse of funds with zero chance of the rightful owner losing their money is a less serious crime than a misuse of funds with a 50% or 100% chance of losing their money.

No, because the crime is the same either way. The crime is "misuse of funds", full stop.

If recklessly using those funds is also a crime, then there should be an extra charge tacked on, which would presumably increase penalties on conviction.

Agreed. I've seen local officials convicted of misusing an offical credit card for groceries and other personal purchases, even though they paid everything back and there was no "loss" to the taxpayers. But they were still misusing public credit for personal benefit.

Of course it was a pretty clear pattern of usage over time, not a one-time thing that could be explained as accidental.