Are you travelling from Rome to Tropea? In that case you buy a ticket Rome to Tropea. You do not concern yourself with the different legs etc.
Just plan the whole trip, and take what the railways offer you.
If you miss a connection because a train was delayed you can take the next available train. if that train is one with compulsory reservation you will need to exchange your ticket however, which you can do easily at the station.
However if you plan an longer layover under the assumption that your first train will be late, and then this train ends up being on time you cannot just jump on an earlier train...
So do not overthink this. Just plan Rome - Tropea on www.trenitalia.com and pick what fits your schedule and budget.