(Thank you for your response.
The problem in the slave training then is definitely the Corruption aspect, and the lack of a direct and clear way to do so. Breaking them is easy enough, and simple, and the sex acts declare that they've been trained pretty quickly. But if flogging unbound is a way to raise Corruption, it doesn't show... and it can get them killed.
As for sex, yes, it said they were trained relatively early on, however I was doing it very frequently, and saw pretty much no way actual change if it was tied to Corruption. Also, the only way to tell their progress was with flogging... and you can literally kill them doing that. Probably will unless they auto-heal. It's not bad that you can tell it that way, but other methods of gauging would be useful so you don't have to worry about murder while stat-checking.
So yes, right now, I'd say the Corruption pace, and ability to tell, is definitely a problem with the current slave training system. Because as of now, I have no idea if any of what I was doing had any effect on corruption whatsoever, and I have no idea HOW to have that effect. Was there something not in those option menus that I needed to do? How would I know?
So that's the biggest problem with slave training in my opinion. The lack of ability to tell progress, or even directly train I think, this Corruption attribute. That needs to be fixed for the illegal slave training to be able to actually be done, much less satisfying. From there, things like time and cost and how much you actually get for illegal slaves, can all be checked. I know how it was in the original, however haven't been able to check this time, as mentioned.)