Hello,
to put everyone in the loop, all current conference payments have been dealt with.
I have sent the LibOCon refund requests to SPI, as well as Italo's refund requests. For the Hackfest, two of the requests are already in the works, for one I still wait for the form, and have seen no other requests so far.
After that, from my POV, we should be done with payments this time, hoping everybody gets refunded soon.
I try to arrange payments for future travel refunds much sooner. Charles also promised to help in the future, so by sharing the burden, we hopefully are faster. 
Florian