Going to monterrosso from Milan 10/4. Was going to buy now. Confused about what “economy fully exchangeable “ means. Does this mean if we miss the train that day due to flight delay we can get the next one?
Are you on www.trenitalia.com/en.html?
If so you can read the T&C of each fare clicking the grey " i " next to the fare name. Economy: https://www.trenitalia.com/en/html/trenitalia/Info_Tariffe_en_LeFrecce.html#ECONOMY
Afaik, the only fare that allows changes after the departure of the booked train is the one called Base.
Since Base is the walk-up fare that you can easily get at the counter before boarding the train, nobody buys such tickets in advance.
Assuming you are flying into MXP, go to the airport station and simply ask for a through ticket to Monterosso with reserved seats all the way.
Ok, You'll pay the full fare of 28.5 € per person to go from Milan to Monterosso, but you won't begin your vacation stressing over delays.