the recurring part of all these FT threads (FCO here, IST yesterday, a rogue LGW last week) is that when you try to fly a particular foreign carrier (AC) back home with at most 1 flight a day you get burned.
Same old story: subcontracted/powerless crews, no irrops recovery, no spare equipment,no reserve crews.
Book your own paid return and AC will gladly evaluate your ticket for possible refund amount. Oops, using their website prices if you had flown just one way you don't get 50% back, you'd technically owe AC $ since price for the RT is likely lower than a single one way.
Odd that this doesn't come up as much in reverse on FT. Lufthsansa doesn't seem to create 48hr cluster***** if a plane goes mechanical or has a medical diversion in North America, etc.
This reminds me how lucky we are that Aeroplan award flights don't require the return segment to be on the same carrier as the origin!