Work has started on it, but we're just implementing one last (I hope!) fairly major shift in the course creation tool - should be running in its new form in a couple of weeks, at which point Iestyn will be able to carry on, and it shouldn't be too long before we start to publish new southern sessions... 
Yes, we do, but if there's a ti/chi shift slipped into the text, it's pretty easy to miss it when recording. It's at the sentence building stage that the hiccup would have happened.
This is usually deliberate - we record separately, and Catrin goes with whatever the text says, while I'll try to freeform known variations into it to give you added exposure... 
That's Catrin getting a little formal when a microphone is in front of her...
In general, she's probably the strongest single influence on my accent, but we certainly don't (and probably never will) match perfectly... 