When a half-orc character rolls a melee critical hit, and via Savage Attack gets to add an additional damage die roll to the attack's damage, the software incorrectly handles it as a second attack. It should be handled as the first attack doing more damage.
The result of this bug is it incorrectly interacting with several other effects. E.g. when a baddie is subject to Hideous Laughter, he gets to roll a saving throw each time he takes damage. If hit with a Savage Attack, he gets a saving throw for that attack, plus an incorrect second saving throw for the extra die of damage.
That is just a general issue with calculating damage: Solasta layers damage from a single attack instead of combining it. For example, if your half-orc character is taken to 0 hit points by one attack and his Relentless Endurance kicks-in to save him (at 1hp) but the attack had additional damage, like a flaming sword with +1d6 Fire damage, it would take him to 0 hit points again but, since his Relentless Endurance was already activated, he would fall to the ground, Dying. This issue affects spellcasters trying to maintain Concentration too: there may be multiple chances to fail a Concentration check from a single attack instead of just one.