No, we don’t know what’s on it. We don’t even know how much of it is past and how much of it is future. Apparently though, Homeworld is indeed a young empire (as far as star empires go, anyway).
More bits from this timeline are sure to make their way into episodes as the series goes on, especially as we learn more about Homeworld. Still, there’s no guarantee that when all is said and done we’ll know everything, since some pieces of lore don’t make for interesting stories.
Hopefully we’ll get it some day. Yes, one can hope.