Age 26 is not a commander of much of anything. Age 26 would be a junior captain in the US Army. Platoon leader. Not a regiment. That’s absurd.
Translation error or Wagner has some different nomenclature for its units. If he was getting 30-40 replacements a week it was company size probably.
Wagner is recruiting straight from the prisons and using human waves of meat even per Russian sources. That’s a high rate of death and probably promotion. And you don’t need a lot of real skills when your whole strategy is to rush the enemy position under the cover of artillery and hoping you don’t die.