Did you read the piece?
It explains why we haven't seen J-20 numbers "ramp up". It's because we don't have anywhere near regular photos of the factory anymore, and because we don't have pictures of all of the in service aircraft but only a number of them.
For all we know they might have been producing a couple of dozen J-20s a year (not that I think they currently are) and we might not know it.
In other words, we don't yet know what J-20's production rate is, so we don't know if' it's already been "ramped up" yet or not, because if it has we probably wouldn't know about it either.
I did indeed read it, I also realize that F-22, F-35, Su-57, FC-31 have all had well published issues which have required time, money, and engineering to resolve... and have indeed resulted in production slowdowns, and even stoppages... each of these programs have resulted in fewer airframes over a much longer period of time than initially anticipated??
Its naïve in the extreme to believe the J-20 has not had similar issues as a "hot off the drawing board, clean sheet design", as well, I'm going to stand by my own observation that even when we haven't gotten J-20 pictures, we've had a great deal of anecdotal evidence when a new bird was rolled out...
I realize China has clamped down on the release of pictures and information, but that has not stopped more credible information from reliable sources...
So thirteen serialized birds that we know of? in each post I have allowed that there could indeed be more, but honestly, I'm extremely skeptical of the "rumors"..
I think the more likely scenario is that the J-20 continues to be like all the other birds, and is requiring more time, money, and engineering to "break through" a threshold, and there will be many more "thresholds" that need to be breached???
as well, the idea that this production slow down is simply the result of "changing" production to the domestic WS-10 does not fully explain it away, changing engines has been very well thought out and planned, just a J-20 maintenance hasn't been a real surprise to the Chinese engineers and technicians, they are very well prepared for all of these eventualities?