What the heck happened to Koth's son?

Koth's son was born in 19 or 18 BBY and was immediately captured by the EMpire. By the time of the Rebels series, he should already be an Inquisitor, right? Is there any Zabrak inquisitor in canon?

Still unknown. This is the last we saw of her:
https://i.imgur.com/jm61kw1.jpg

That makes it sound like the Empire had some sort of program where they were collecting force sensitive children for some reason??

I'd imagine they were doing it to create more inquisitors, but it might connect to how Moff Gideon wants the Baby from The Mandalorian.