Why didn't you send the dumping hardware to the PAL donor? This makes me think of another idea to avoid shipping the cartridges themselves around: an interface that allows eventually accessing them over TCP/IP. It could be exposed as a block device or a custom protocol, it doesn't matter as long as you can essentially send an address and get some bytes back, allowing to read the entire address space.
And you need them to look like this:
That takes about a half hour's work. Then you get to open the cart and clean the contacts, another five minutes. Then once it's connected to an SNES and powered on, you have to wait 5-10 minutes to dump it, and then move on to the next cart.
It's a full-time job for several months to do a complete PAL set. And that's not even counting scanning the boxes, manuals, cartridges and PCBs :/
It's a lot less effort for the donor to send me his games, and I send them back, and reimburse him on his shipping charges.