It's a bit confusing because Jim almost contradicts himself, then recovers. Having seen Jim get a bit confused over his own stuff a few times I'd be willing to bet that he was a bit confused then too. Which isn't to say that what he said isn't true. But it sort of contradicts other WOJ on Dragons.
The link you posted occurred a few years after those questions were answered, so being the latest information it's more likely to be true. But it seems strange that Ferro and Sirio and Pyro are both semi-divine beings in the more Asian sense of being Dragons (as in capital-D Dragons) yet also are the workers and Western Dragons...and yet there are also lower tier servant (lowercase-d) dragons who are just emissaries and workers themselves but are mostly just beasts. It just seems like too many concepts have been confused.
Myself, I think the questioner (I forget her name) confused him. I don't know where she got the idea that Ferro and Pyro were Western dragons - because prior to that video as far as I know there was no indication of that. So either she was privy to information moist fans didn't have (maybe Jim told her something) or she was confused herself and asked Jim a poor question which caused him to give a confusing answer. I don't know what the case is though.
Also, his terminology that there is only three before Michael killed one left is interesting (and further evidence of contradictory information on the death of the dragon). Could it be that there were quite a lot around at one time. Not four or five or six but perhaps a multitude?
I'm not seeing much conflict between the video and the previous comments. Maybe he said at some point that there were four and only four Big D Dragons, but I think it's just how we interpreted what he really said.
In all, there are likely a bunch of Dragons, Asian or not, that are still being Cosmic Avatars. They're doing their job.
A handful, specifically four (or five) were disgruntled workers among the other worker Dragons, and they descended to Earth in earthly forms. Those were Ferro, Sirio, Pyro, and the unnamed fourth. And possibly Lucifer.
For all we know, Dragons might be Angels, or Angels might be Dragons. The earthly Dragons might be the Dragon equivalent of the Grigori or the Fallen. (I'm not saying they're either, just the Dragon-pantheon equivalent)
So only two remaining on earth doesn't preclude others not being on alive but not on earth.
As for European vs Asian, it could be that the Four were responsible for European regions (like Grigori had specific tasks on Earth) and they kinda sorta transubstantiated, but the Asian and other Dragons kind of tsked and went about their business.
...
Or, be hedged his answer to avoid accusations of euro-centric mythologies being predominant in the series, and tried to give an out so as to not offend anyone.
