My take is:
1. They are definitely over-hyping on the number of DF-21D, possibly only two coastal brigades operating them. Same story are happening on DF-16 counts, only two brigade operating them.
2. They are underestimating DF-26 by a huge margin!! There are 5 - 7 brigades operating DF-26 series. Suppose each brigade gets 24 launchers and another 24 re-loading missiles. I would say at least 240 DF-26s currently in deployment and possibly over 400 if each brigade get more re-loading missiles, which is the most likely case.
3. However, I think the combined number of DF-15 + DF-17 could be very close to the true number. First of all, DF-17 has the cheapest booster stage in PLARF inventory and the bottleneck is the HGV warheads here. I am not sure if they have already produced 500+ warheads since its induction 3 years ago but I am assuming that DF-17 is replacing DF-15 by a one-to-one basis and is going to have a huge number of inventory.
4. WTH is even HN-2 and HN-3?