Ca va, ça va Rudyard,
About MLAIC I prefer forget it : all is historical when it goes in the good way (the MLAIC way of thinking) and bad if it’s in another sensse that the MLAIC will, I have seen that sometime with arms and accessories…
You are certainly right when talking of the japaneses weapons, the Portugueses, the britishes and the Dutchs.
The first, by décision of the pope, comming in Japan were the Portugueses and after the Spannishes.
After the battle of Sekigahara only Will Adams (english working for the Dutch company), man that knew Tokugawa Ieyastsu an become samuraï have right to stay for exchange and buisness. In this time the matchlocks were presents in Japan and at the Sekigahara battle, the battle that Tokugawa Ieyastu won: those musket have never changed in style till the XIXth century at the end of the shoguns and the coming of Meiji.
In this way of consideration the Portugueses muskets, certainly inspired by other like, why not Venicians, are the first japanese matchlocks and the only great differency the metal : brass at the place of steel and iron…
So, after all and after looking the Portuguese musket we can see that it’s not issued from Venice (the region) only but also Germany, France, Spain and Dutchland, it looks like a mix of all that…
Anyway that have no agrement for shooting in Tanegashima or Izadaï for the simpliest reason than it is not in the synoptic of the MLAIC while the Tryon handstand is accepted (just one example MLAIC) ...