The Core Rules define Action limitations "...only one Attack and one Concentration Action per Turn...", then the description of Lightning Attack throws this straight out the window. Swift Attack doesn't get the same love as Lightning Attack...until you read the Two-Weapon Fighting rules.

I'm having trouble accessing the errata. Looking at Only War, it seems these inconsistencies have been addressed. What gives? Has this been nipped by errata or not?

The Lightning/Swift Attack talent descriptions are errata'd, if that's what you're refering to.

Also bear in mind that many traits/talents allow you to "break" the rules by giving you additional atacks when you shouldn't have had them, changing required rolls, giving you re-rolls and so on.