I have not travelled yet, but I already have bad experience with flight change.
Two days ago I received cancellation email for Frankfurt to Narita leg of the flight from Helsinki to Sydney. They moved me to the earlier date effectively killing the Helsinki to Frankfurt leg. So change of flight was done with disregard to my itinerary. Worst thing is Helsinki to Frankfurt leg being operated by Finnair, but still booked through JAL and paid for.
Later they moved Haneda to Sydney leg for later day increasing our layover by 24 hours.
And one more thing:
Change the terminal from Narita to Haneda seems not possible with current government regulations. But the system let that booking through.
So looks like we are in trouble now, have to ask for refund for return to Sydney flight.
Two hours on hold calling the Australian contact number, still not getting through.
What a nightmare