in terms of coding, there are aspects of the game that the developers can look into and simply "copy and paste." This very much applies to many characters physics attributes and frame data, as well as certain equations that dictate how the engine functions. in certain cases like these, you would see equations built into the coding for melee, and instead of writing out an equation, loop, or function straight from scratch, you would just use the fact that its already written in the game youre studying.
in terms of the specific use of the word "ported," this is a word that has very frequently been used by the developers to defend the fact that certain gameplay mechanics/stats are the same as melee. if anything, their usage of the word would imply that certain things were, in essence, copied and pasted, instead of tediously written out from scratch.
Additionally, I hope with the abundance of my questions in my posts youre not thinking that im assuming or implying anything. They are questions for a reason, and I am not implying that I have enough assembly experience to assume how they pieced together the game, or how a lot of details of the games architecture work.