Well atm nobody with authority is there to question him. They would probably raise eyebrows at the AI who was meant to delete herself not being dead, looking like Cortana and who they know is a copy of her. People are going to question him on this regardless of what she’s called.
Honestly judging by the marine banter there’s almost no reference to the Created or Cortana. So, I don’t think they’re going to panic if she’s on the Coms.
Exuberant Witness isn’t in the game…
Infinite isn’t an echo of previous games, it’s a full “we dun goofed” ctrl+z undo of the previous two games.
Either way, I highly doubt she’s going to be named Cortana.
Another possible name that she may have is “Joy” as that would come from the same origin as Cortana’s name:
Curtana
Durendal
Joyeuse
For those who don’t know, these are the names of three mythical swords of medieval legends. With Cortana coming from Curtana and Durendal already being referenced several times in the series as well as Marathon, the only one that hasn’t been used is Joyeuse.
Given that we have an AI called the Weapon and one out of three names of mythical swords that have yet to be used…
I was just writing this!!!
You beat me to it…by seconds.
Haha, I’m sorry. I just happened to see the possibility not too long ago and decided to share it here 
Ok, I didn’t know about that. Now I’m questioning my own theory lol
Joyeuse is a very possible option after reading all that.
Wait shouldn’t her name be red flag 
Red Flag was one of two of Chief’s passwords for the deletion process. It actually references Operation: Red Flag which was an UNSC ONI operation that was meant to end the human-covenant war. The operation was delayed and adjusted due to the fall of Reach.
So it doesn’t really fit here.
Nah she’s gona name herself Avery Johnson
Makes more sense to just call her Cortana. Echo just sounds like a bad generic name and people just want a memorable name that isn’t forgettable so most people will probably just end up calling her new Cortana but I guess they could call her neo Cortana to separate her from the original. 
That’s the first definition.
I meant Despondent Pyre
Haha, I’m starting to hear a lot of echo in here (yes, I can be puny).
Yea, I mean look at the cosmetics, they took 38 of the 48 default colors and put them behind a paywall and just re arrange the color scheme a little and boom you get a different color brown buts it’s the same brown just this one has more brown on the helmet.
Haven’t been to impressed with cosmetic ideas for the coatings so far.
She is going to name.herself Keys…
Or Miranda …
Remember of all the echos, when Keys started to talk she asked specifically who that was.
And Miranda is Halsey’s Daughter so Miranda would be a fitting name for the second version aka daughter like version of Cortana
Sometimes the simplest explanation is the correct answer. Thus I believe she will name herself Cortana.
Fernando: And what about you?
Weapon: What about me?
Fenando: What do I call you?
John: Any ideas?
Weapon: Well…
Weapon: *puts down arms, and in an almost sympathetic way says* …Do you think it would be okay?
John: *nods*
Weapon: You’re sure?
John: You get to choose your name.
Weapon: *in a slightly hesitant but optimistic way says* Then… I think… I think I might have the perfect one.
Honestly. I don’t see how anyone can look at that and go ‘‘Cortana is too obvious, it will be something else’’.
It is obvious because it will be Cortana. She picks Cortana as her name because she is technically Cortana but also to prove to herself and John that she is more than Cortana and at the same time that she isn’t Cortana. She isn’t going to become the person Cortana was, she is going to be better.
Yup. She is Cortana if 343 had never decided to turn her into Chief’s girlfriend, kill her off, and then resurrect her as evil because reasons.
It’s a fairly intelligent way to retcon two games worth of awful story.
Halo 4 & 5 are both great…story and all.