Thanks everyone - especially for the note that if arriving at Terminal C things should be ok. I did a little checking & it seems this flight has landed at C in the recent past so hopefully it'll also be the case for my flight in 2 months.

As for the re-route to SFO, I have another final connection after. Being at SFO vs LAX is an added inconvenience and gets me home a lot later than originally planned, but I was more concerned with the connection time at EWR (I didn't want to over complicate my post by adding that to the story). I haven't yet called United to ask about this arbitrary change. I just happened to notice it last week when I looked at my account (no one has bothered to contact me, notify by email, of the change). Two weeks ago I had issues with a separate flight from Rome getting cancelled multiple times also for no apparent reason & also no notification. I spent a whole weekend on the phone with United fixing that mess that I just hadn't mustered up the will to call & spend more time on the phone with them. I figured if the EWR connection time was doable I'd not worry about it, at least for now. So I'll hope for a C arrival. Thank you so much!