To send data using a client to a specific server, you need to start the client with the -i flag, passing all the necessary servers.
West server command:
albiondata-client.exe -i
East server command:
albiondata-client.exe -i
For convenience, commands can be written to a shortcut and run the client through it.
⚠️ WARNING! Custom servers can't tell a European server from an Asian one. When switching the server in the game, also change the server to send in the client. Otherwise, the data will be stored on the wrong server.