Wells Fargo bank can only accept transfers of USD to their SWIFT.
To transfer Euro to them, it has to go via an intermediary bank (Deutschebank), with the beneficiary bank and their SWIFT, and my account name and account number all included in the transfer instructions.
I also tried Transferwise; to send Euros to my account there, the transfer has to include a reference number that they provide.
No way to do any of that with the #Liberapay form, so my EUR is stuck currently.