Update:
With Withwnar's TW Map Utility and with Gigantus' help, I have relocated Ngala, Azande, and Lusaka. They were absorbed by neighboring regions in Africa.
I then created Kagoshima, Kochi, and Iwate. Japan currently has six settlements (Kyoto, Edo, Kagoshima, Kochi, and Iwate PLUS the ahistorical Sapporo). My plan is to make Sapporo an Ainu slave kingdom held settlement. The other plan is to make Kagoshima, Kochi, and Iwate to be Ashikaga held samurai daimyo, thus a direct existential threat to the Hojo Shogunate. I can configure it so that they have peaceable but severely strained co-existence, or script it such that they are vassals, or script it that they wage war on the Hojo.
As 31 Kingdoms are already in play, then the most likely candidate to reconfigure is Indochina. Given they can only make two unique units, the benefits of seeing Japanese history play out outweigh that limited expression of Indonesia's warriors. It's that or reconfigure Lithuania or Serbia as neither probably has much of a chance to establish a growing kingdom, while Indonesia can expand due to its isolated spot on the map, plus the border clashes of the Yuan Dynasty, and the new civil wars in Japan.
Thoughts? It certainly makes playing as either the Hojo or Ashikaga extremely difficult, like the English vs France historical wars. Since the 1326 campaign is configured as an AoR, and many people have mentioned turning that off, then I might make only the Hojo able to use an AoR, and the Ashikaga strictly xenophobic and only able to make samurai units (no gun tech from the Yuan if defeated/ no better armor from Europe).
In 1326, the Hojo Shogunate were making diplomatic inquiries to the Yuan Dynasty regarding trade, cultural exchange, mutual assistance versus the Wakou pirates, etc. The then Yuan Emperor (under a Mongol domination that wasn't to last say past 1360 A.D.) was addressing the King of Japan versus the Emperor, and hence yet another province of China. Such things helped contribute to the rise of the Ashikaga and outraged and emboldened the newly forming daimyo [The not well known name for these military governor precursors was the shugo.]. The daimyo simply didn't have the military and political power yet in 1326, but did as a result of banding together to depose the Hojo. The Hojo committed seppuku in history shortly thereafter, but anything might happen after turn #1 in the submod.
It certainly makes sense to look at the armor upgrades of at least the Samurai, No Dachi, Samurai Cavalry, and the Samurai Bodyguards. Upon contact with Europeans in the 1500s, cuirasses were purchased and traded. Then copied and modified and lacquered. They became incorporated, even "proofed" with gunpowder weapon tests to ensure that no ammunition would penetrate them (versus their own armor technology). There's enough armor classes configured versus history to included several upgrades to the current maxed out laminar armor class of 13. Certainly splint was utilized up to the cuirass point, but then stalled from then versus European armor.
Upon capturing some of the more powerful Yuan settlements, you'd expect for an absorption of the Yuan Armor of their units, one of which exceeds 13 i.e. the Song Shield Gunners with 15 and later 18 armor class upgrades. 15 requires a heavy_armourer (which of course the samurai had for 13), and the later 18 is a function of the plate mail event and a plate_armourer to achieve the 18 value. So this is where the new upper limit would be for the samurai to match history or only if lucky enough to have exposure to the Europeans plus conquer strategic Yuan strongholds.
Proofed test of a samurai's curraised armor (Namban-do gusoku) plus obvious battle test. Not uncommon circa 1500+ AD.
The armor classes utilized in the 1326 campaign.
Since I am no modeller, unless one steps forward, the samurai have the potential to upgrade up to 18 upon certain conditions, but the unit depictions will not change. It's a small thing, but if somebody feels like volunteering these four armor class upgrades, then you'd see that reflected in the submod campaign.
Update:
If the Empires campaign is equally popular, I can edit it to be more historical versus the godlike Spanish configuration. Certainly see Japan and Joseon to be as accurate as possible within the hard coded limitations of maximum unit and region numbers. When I reconfigured it before, Spanish territory in North America was inundated by indigenous Native Americans.