As per RAW, fighting with two weapons should only allow you to attack with your bonus action if you first attacked with a simultaneously held light weapon using your main action.
In Solasta, you can mix and match as you please while dual-wielding. The problem mostly lies in the fact that the bonus action attack (= off-hand attack) is selectable without having first attacked with your main-hand. The way it works right now you can use your BA to attack with your off-hand, switch your weapons to e.g. a bow, and attack with your bow using your main action. That shouldn't be possible. Therein lies the second problem: as soon as you switch weapon sets, off-hand attacks should be disabled I think.