Sorry - I've not really been monitoring this forum, but I have just popped in to see what's going on. The short answer is that the commentary is moving forward slowly but encouragingly; I've recorded around 20-25% of the lines of commentary which will ultimately be included in the game, and I'm happy with the framework for how some of those lines will be incorporated in the game.
One of the ways I'm trying to keep things fresh is to have a lot of commentary lines which can be split into two parts - for example, I might want to say "[Player X] is hitting the ball beautifully," but in place of "[Player X]" I could potentially say "The American..." or "The lefthander..." or "The world number 27..." or "The teenager..." or "The underdog...", and so on. To facilitate this, I need to have a system whereby I can ensure that the two halves of commentary fit seamlessly together, and also to make sure that each half of the commentary isn't used too frequently. I'm confident that I've solved both problems, but it does take a long time to record each commentary segment and test it against the other half to make sure the transition is as seamless as I can make it! (And also I'm recording nearly all of these lines twice - once in a normal tone and then again more enthusiastically - to ensure that they fit the match situation and the amount of crowd noise in the stadium.) I really hope everyone will be happy with the end product, particularly as I don't think any other tennis game has tried some of the stuff we're trying!