Hi there !
(TLDR at the end)
I think we have all been on the giving or recieving end of a Daimyo pop.
While this is not a balance problem (imho), it feels frustrating and not really interactive.
The guy rolls in, your goons rush to stop one guy before a military shipment comes out of under their horses to blow up all the infrastructure in the world.
Either you kill them and you used a very high chunk of your army to stop one guy, or you don’t and he has free reign over the back of the base. Even behind walls, the guy can pop morutarus, which will do +25% damage to walls next patch.
So here is my very simple proposal :
Give all Daimyos the Hero tag
This would enable Spies or advanced scouts to do wonder against them, but also may enable the daimyos to detect Stealth, benefit from hero bonuses techs, and even give maybe a hint of interest to the Spanish Destreza card. Note that the flag KnockoutDeath is different from the Hero flag, so you can have heroes that die, in this game.
We could even see specialized anti-japanese decks make use of the Assassins card. It makes sense, gives another niche meaningful role for spies, that slighly increases the unit’s value, and enable strategy-focused players to have 2-3 pre-emptives spies to punish this.
From the Japanese player’s perspective, these Daimyos are now buffed by Hero-buffing techs. As they are now trainable from the wonder and thus loosing one is much less punishing than in legacy.
TLDR : Giving Daimyos the Hero tag enables new buffing ways, engaging counter-play, and rewards adaptability, while giving the Japanese player better anti-stealth options.