Don't know if you solved it but i got it running by simply installing libqt5serialport5 from terminal:
sudo apt-get update
sudo apt-get install libqt5serialport5
I've been using the latest ReiNX with exFAT for weeks now and haven't experienced any issues. Some crashes here and there but nothing crucial or corruption.
Freeshop doesn't install tomodachi life properly either, install tikshop instead and wait for it to download all tickets then go in to eshop and download tomodachi from there