For Fire Emblem Fates, if you win at my castle battles, will you able to inheritance from other units with skills if you update the data on internet or no? Answer.
In order for us to provide better support, we need to see the log generated by Citra. This guide will walk you through how you can obtain the log file: How to Upload the Log File.
I haven’t played the game before so I’m not sure. If it requires connecting to Nintendo’s servers though, its probably not going to work. You’ll need to transfer the save file to your 3DS using Checkpoint, acomplish the network task there, then import it back to Citra using Checkpoint again.