In case you wasn't able to resolve your issue with fastspring support, you can always contact me directly, I always reply to every user.
evatte:FastSpring is a payment processing service based in the US and has nothing to do with Eugene's work. And no, he's not able to know what went wrong. Also his bank account won't have anything until FastSpring sends out the donation funds to him once a month or so.
He is that site owner and probably made the payment site himself, he should be able to know what went wrong and check with his codes, or at least check his bank account to confirm the payment is there or not.
If you're wondering why Eugene chose this service over PayPal for example, there is a very simple explanation. He lives in Ukraine and PayPal cannot be used there to accept donations (or any other kind of funds). FastSpring was the only working and reliable service he could use at the time.
I'm quite certain Eugene actually cares for all his supporters and will try to help you in the best way that he can.