.But the relevant point is that the absence of pain is the important part, rather than any kind of quantity of pleasure or something like that.
If taken literally, this would be a statement that "absence of pain" is a totally separate thing from "any kind or quantity of pleasure" -- in other words - absence of pain is not pleasure at all. Is that your view?
It would probably also be helpful to know more about what you mean in your words as the "additive concept of pleasure." It would seem clear that Epicurus is saying that it is not necessary to add ever-increasing quantities of pleasure ad infinitum to have a happy life. But on the other hand he is also saying that pleasure alpha / omega / goal of life - that a life of happiness is a life of pleasure - so obviously some measure of pleasure is involved.
How would you renconcile those perspectives?