Since it’s really several separate issues, I’ll group my thoughts on each separately:
1. ANZAC Roundel Issue: I prefer the Kangaroo one, even thought it’s ahistorical, and won’t match the board. My thoughts are that FMG’s pieces and dice aren’t JUST A&A, but general-purpose WW2-era strategy-level game parts that could be and will be used on all sorts of different boards. What’s more, having such a difference would help you make the case, should WotC ever try to sue you guys for copyright infringement. This is the issue I’m most wavering on, though, because I can see the argument of those who want this gear to match at least the board… (As an aside to the curious, I did some research on the new ANZAC roundel and found that it came from a hat badge made famous by Aussie troops in His Majesty’s service. I still prefer the kangaroo one, but at least I know why they chose it now.)
2. Change the colors, I think. I suggest the light green from the earliest versions of the WotC variations would be a good one. (If you’re not sure which one I mean, it’s the one TT used for their British units, and it’s kind of almost half-way between the US green and the UK tan, but I think easily distinguishable from both.) On the other hand, whatever you do, don’t go with white! White would be a good neutral color, but even the WotC grey-brown would be better for the ANZACS! (As an aside, I picked up a copy of AAP40 today, and, fortunately, it’s at least not a pure grey, but more of a greyish, tannish brown, which was a considerable relief to me.)
3. French roundel: use the French aircraft roundel, which is like the British one, but reversed and without the yellow outer ring.
4. French color: definitely blue. Which shade, I’m not sure. If there’s some way to find out what WotC is using, I’d say get it close. (Assuming that they use blue… if they happen not to, use blue anyway. Horizon blue was actually, I think, somewhat obsolete among the French by this point, but it still makes for a recognizable and iconic “French” uniform color, so I say go with it if WotC is going to do something strange again with their colors.)
5. Now that I’ve actually seen the new ANZACS “in the plastic” I say keep issues 1 & 2 linked… If you change the roundel, change the colors, because both are, after all, an odd choice. However, the color isn’t quite as bad as I’d feared, so if you’re going to keep the roundel, maybe staying with (or close to) the color would make the most sense. (I know that you’ve said that the Italian color you’re using will be slightly different from the AAA Italian color and thus a little more easily distinguished from the soviet color… you could do something similar with the ANZAC color by making it a little more brownish, perhaps, and a little less grayish.)