I have come across edits (plenty of examples out there) in which the author hadn't added any salutation in front of the name of the Prophet (saww), Ali (as) etc but somebody comes by and adds it.
Do not do it.
It's a matter of taste/believe/conviction/choice (call it foobar). If the author didn't intend to add any. You shouldn't either. (From the SO lens it's like changing the style/indentation of a piece of code. Which is discouraged AFAIK.)
It's not part of the editing spirit and could be seen as reflecting/imposing one's foobar on that of the author. And might also be unwelcome to the author.
You're welcome and encouraged to make valuable post-improving edit. But don't make this part of your edit. You're not mandated nor supposed to.
If a salutation/prayer/wish is added, or not, don't change it according to your foobar. Adding in case of absence is also considered as changing.
E.g don't change:
"Prophet" -> Prophet (saww) or Prophet (PBUH)
"Prophet (as)" -> Prophet (May Allah be Pleased with him)
What's your say on this fellas?