Update regarding the AY102 schedule change - I used the AY web chat to ask if it was possible to change the flight due to the departure time moved by 1h30, and it seems the agent was able to change my return to the next AY100 for free.
I'm waiting for the confirmation e-mail - the change is already visible on AY app and on checkmytrip - but if it indeed works, I'm very happy.