but it is not necessary to look at them, for me they are black boxes, I have no idea of c ++ it gives me chills to look at written code.
I do not know very well what you mean, if you use a pluging it is because what it has is already valid for your project.
The first thing to advise is that you decide on the engine based on the game and the target, but the OP has not made it very clear.
Yes, I would not advise a multiplayer game, unless it is a prototype, if you do not know C ++ why you ended up getting to touch things. But games only with bp are an empirical fact, and if they have already been released you have no dependencies on the plugins that you use.