Uncommon to the point that most people consider them more a mythological being. And much like any mythological being of old, there are hundreds if not thousands of orc hopefuls who claim to be a decendant or even an orog themselves, to mixed results. The issue with orogs is that there's a lot of discussion about what exactly makes an orc an orog; is it greater than average intelligence? Is it it being bred with an ogre? Is it simply divine blessing? All these things are just one of the many things that orcs will fight among each other about.
Mechanically speaking by the way, the orcs in Keratia are not Volo Guide's orcs, but Eberron style, which mainly means two things: instead of simply Intimidation they get Primal Intuition, which means they get two skills proficiencies (Animal Handling, Insight, Intimidation, Medicine, Nature, Perception, or Survival). And secondly, they don't have the innate -2 int of the Volo Guide orcs, so orcs in generally are not any more or less stupid than other races. It's for this reason that the orcs in Keratia are fully capable of creating and maintaining their own forms of government and diplomacy, but also still have the same issues as any other nation when it comes to conflicting ideals and cultures. Incidentally their Primal Intuition also means that there's a large variety of skill among different orcs, which encourages a sort of tribalism to stick with people who are good at what you're good at, but also competition where orcs would want to be better than their fellows by whatever means practical for them.