I never suggested that a ‘different’ organism - much less a different species! - had been ‘created’. And yes - the term ‘gain of function’ indicates an enhancement of what is already there; it doesn’t indicate ‘gaining A function’, which you suggest say presents ‘no difference’ in meaning.
You know what? I think you should find the person who named this type of research and tell him/her that they were very mistaken in their choice of terms. I’m sure that will be a much more satisfying argument for you.
A human being can gain a function that he/she did not have before. Body building can make a person a lot stronger than before. That’s gaining a function. A virus that is enhanced is gaining a function, with the same properties it already possesses. So, why should it be called ‘gain OF function’ when it’s just enhancing a property that already exists in the organism?