Nope, only fromaĝo takes the accusative case, hence the additional n. Kun vino simply attaches itself to accusative form fromaĝon,but is not accusative case itself (it's instrumental case, actually; but that's irrelevant for Esperanto because there is no declension in that case -- the noun stays the same!).
But I understand your confusion. The whole phrase fromaĝon kun vino is in accusative here, but only the "main" word from the phrase takes the -n ending.
Why? It leaves space for turning other words inside the already-accusative phrase into accusative case! If you added -n to the whole phrase, it would not only be too confusing (it could be a very long phrase!), but it would also stop you from marking other stuff inside it as accusative again. :)
Lazar95 has a great explanation higher up in this thread, but here's a short version in case you missed it. 1. Only the "main noun" in an Accusative phrase takes the -n. This allows for further use of the Accusative case, nested within the main Accusative phrase. 2. "Kun" would trigger the Instrumental case, if Esperanto had such a thing. As such, "vino" does not require the Accusative -n.