This is only my interpretation but since almost every progress report had the "total" number of tasks increased for awhile, this new extension just means the the devs finally got able to tell how many more tasks they will be doing until the end of the development.
As you can see those "total" numbers haven't increased for the past 4 reports, not saying that they may not had more until the end.
So what I mean is that 950 total polish tasks to do now would still be 950 tasks on the end of development considering that they just keep adding them along the way, the only difference is that the % progress now represents the "real" amount of work they are doing while the same couldn't be said before.
