Yonder is a good (if dated!) translation of acw / dacw - it is used for things visible but out of reach (and a long way out of reach!). But I've certainly heard the hwntws using 'co (= (a)cw ) for general yna / dyna (see below) instead, so they don't clearly don't agree! They say things like 'Co fe! for There it is! - meaning there on the table, for example.
Yna / dyna is there for anything closer than that, while yno is there for things and places so far away that you cannot see them.
They're all in the Grammar at §§418, 419