I love this plugin and it's got me pretty excited about designing elaborate shield-use mechanics in my current project. As a quick note, the demo project requires but does not include most of its plugin dependences (I presume this may be in part due to Yanfly shifting plugins in part behind pay requirements.) Figured I'd give you a heads up though--if all else fails you could have a 'packaged' demo so someone can try it out without having access to those additional plugins?
In the meantime, I noticed that you'd played around with a 'flat-footed' state, though I didn't see it used in the demo near as I could tell; I love the prospect though as it pertains to blocking--and also, potentially, parrying.
I was curious as to how you might suggest going about implementing such a state as a thought exercise--I figured it could be set to auto-resolve after an action is taken, to represent the actor being ready to receive attacks, but I'm a bit on the fence for implementation when it comes to how broadly to apply the state and when.
Presumably, via Yanfly passives or otherwise, the flat-footed state could auto apply to everyone and then fall off as actors perform actions; this could be trimmed down with a qualifier for only applying the state if a given actor -also- has the 'blocking' state, since a reduced block chance isn't relevant to actors who can't block in the first place. However, if a theoretical flat-footed state also applied to parry chance, that gets a bit broader.
Overall not necessarily too huge a deal in the context of 'actors are flat-footed when battle starts'--but it does open the door for more D&D-minded mechanics like sneak attack, etc. too--with actor abilities that can leave an actor 'flat-footed' for however long and dealing bonus damage or whatever other effects as a result. Just food for thought!