So it seems pretty well established that most routings (LHR, DFW, ORD) rarely have I5 or better in July. The CLT routing seems to be the lone exception here. So here are dates with I5 or better with YVR-CLT-FCO routing in July (example for July 1 below) according to EF -- July 1, 2, 5, 6, 7, 8, 9, 15, 16, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31. I'm assuming one of those dates should work for OP (as long as they are before ticket expiration). Otherwise, OP will likely be stuck paying fare difference if looking for more convenient routings due to lack of I5.