I'm not a WWII gamer, but as an outsider, it sounds to me like Finns, Romanians, Polish, and Chinese definitely sound like some niche armies that probably don't get a lot of attention out there.
I don't know very much about the ANZAC uniforms, but that request for shorts uniforms might be an opportunity to cover the seemingly popular (or at least vocal) ANZAC requests. I think the shorts request thing from otherwise depends on how niche that would be: I don't know for sure, but I suspect it's mostly specific to the North Africa and Pacific campaigns.
Regarding the market for Asian armies and whether they sell well, I can't help wondering if that's a chicken-and-egg thing: is it struggling from a lack of demand, or a lack of supply? To be honest, I'd never really thought of the Asian gaming market at all, until I got surprised by the popularity of video gaming in e.g. Korea, and then again later when I was surprised by the popularity of pen-and-paper and computer RPGs in Japan. Video and pen-and-paper RPGs don't necessarily translate to a tabletop wargaming market, and even if it does it doesn't necessarily translate to a specific interest in the Asian/Pacific theater of WWII, but there might be a surprise market for tabletop gaming of some sort in China, Korea, Japan, or India that I wouldn't expect.
For my own part, I'd love to see more multi-purpose Partisan-style sets that can find their way into either historical or "pulp" sci-fi/adventure/horror/fantasy gaming. Such a kit that includes bits that could build adventure achaeologists as easily as partisans in similar outfits would be fantastic, and I too look forward to a female partisan set, if that's what Wargames Atlantic has planned for Parisans II - of course, they could just as easily be planning a set of Partisans from another part of the world, too - say, Russia or Poland, for example, or even a set of different male French resistance fighters for greater variety, or even Partisan fighters from other wars.
All of which would be quite welcome, to me: the Partisan set is great, and I don't think gamers have even begun to take advantage of all the possibilities from the first set yet! (I came into the kit for the civilian bodies, fedoras, bowlers, flat-caps, and bare heads, but stayed for all the other "bonus" bits I didn't notice at first: the wealth of SMGs plus the soft hats like the berets and "envelope" style hats look like they'd fit right in with historical military armies. I don't really do historical military gaming, but I did save these hats in my sci-fi bits-bin for use in sci-fi military modeling: berets for space-commandos or Cannon Fodder officers, for example!)
For my purposes, then, I think I'd be interested the most in some more WWI/WWII/interwar Partisan/civilian sets with kitbasher-friendly multi-purpose bits in them, and perhaps in some period security forces as well - things like Vichy Milice, brown-shirts, civil defense, Gestapo, generic police forces... these won't make much sense to larger-scale war-gamers, but for smaller-scale skirmish games of commando raids, conflicts with Partisans, and the like, as well as pulp-style gaming ("cops and robbers", gangsters vs. revenue agents, police vs. rioters, police vs. Martian invaders, spies vs. spies....) Something tells me that things like police uniforms or Gestapo men in those creepy hats and long coats would probably make their way into more than a few unusual contexts for both historical and other games: paramilitary organizations, villains in space-dictator armies, monsters in fantasy RPGs ("The Shadow Man"), etc.
Or it might just be me. Hopefully the Partisans are successful enough for Wargames Atlantic to make more odd subjects like that, because it's one of my favorite Wargames Atlantic sets! :)