Neither did Canon or Sony reveal the number of their 600mm F4 lenses being sold! You are probably aware that exotic lenses is a high profit margin low volume item of most manufacturers! The number is nothing to short about.
Even for the Olympus 150-400, I don't think it is more than a few hundred sold. What is the point of announcing the figure?
BUT, why are so focus on such minute details like country of manufacture or how many units sold?
It makes me wonder are you even a photographer?
You basically just shut yourself off to the possibility that the Olympus 150-400 is being able to bring to you some additional perspective of photography which may not even be available in Full Frame cameras. Go and look at some of the photos shot by the Olympus 150-400. Then comment on how are they compared to photos taken by the closest telephoto lenses of other manufacturers. That would make the discussion more fruitful than to discuss on silly details like Country of Manufacture, as if lenses make outside Japan or Germany will take very bad photos.
Sometimes, take a step back and look beyond the self-congratulatory press releases that sounds like:
• MFT is #1 in Japan (based on "in-house survey")
• Our sales are so good that we cannot keep up with the demand
• We are overwhelmed by the orders for our super lens
• We have in line a range of super attractive products for you to buy
The REALITY is something else.
Otherwise there would not have been any need to divest the whole Olympus Camera Division to JIP in 2020.
For example, what about the actual numbers of Olympus 150-400mm f/4.5 TC1.25x IS PRO M.Zuiko, sold so far.
And the projected numbers of such lenses they expect to sell from 1 Jan 2021 to 31 Dec 2021.
If they are really selling beyond expectations, it would be an obvious marketing effort to proclaim this all over the world in boastful advertisements.
It seems that so far there is Dead Silence on this.