It's strange that the FBI said they couldn't do anything for her unless the scam
artist is on American soil.
I don't know how the jurisdictional rules work, but there have been plenty of instances where the FBI teams up with others to take down international scams. One example:
The FBI partnered with domestic and international law enforcement agencies on Operation WireWire, a large-scale, coordinated effort to dismantle business e-mail compromise schemes.