Ein interessanter Hinweis diesbezüglich stammt aus dem Rezensionsvideo von Beckikaze: nämlich, dass sich die Kappa im Kampf sehr generisch anfühlen, obwohl sie von ihrem Verhalten her einzigartige Charaktere sind. Wer zum Beispiel die Yokai-Enzyklopädie von Shigeru Mizuki, seine Mangas oder andere Darstellungen kennt, weiß wie originell diese Figuren aussehen und agieren. Das macht das Thema doch gerade so spannend!
I'm curious, what behavior would you have given him?
Would you have created an underwater mechanic? Underwater tiles? Would you have created children tokens to save them? Would you have created cow tokens to feed them (yes, if I remember correctly they hated cows xD).
Oh and of course we have read the great “Yokai Encyclopedia” and yokai.com and “Yokai: monsters and ghosts in Japan” and a long etcetera of books on Japanese mythology.
Right now, the humble Kappa is a very generic fantasy melee enemy, and that's it. If you removed the model, replaced it with a goblin, nobody would be the wiser. You place them on water, but that initial setup seems to be the main connection to what a Kappa is. The rest is generic fantasy melee.
That works as a generic enemy, but lacks kappa flavor other than the name. The flavor is all in the model, and not in the abilities. Even the attacks you gave them are entirely visual, working on descriptions of what a Kappa looks like, not what a kappa does.
You can still have thematic mechanics for a simple enemy, for example:
-Lower movement on land, much faster on water tiles (perhaps even free movement on water tiles)
-a mechanic like one enemy in Middara had, the ability to "hide" in water tiles, by not being attackable at range while in water
-what about wrestling/grappling? That's a mythological cornerstone and absent here. They could have grapple attacks that prevent movement and do extra damage when on water
Just giving them grappling/pulling enemies to water for extra damage, and much higher speed on water, would probably make them feel much more like Kappa and less like [Generic Melee enemy 2]. It would also lead to more interesting encounter design involving Kappa.
I think this is a much more valid criticism than Wukong/Daji/Mulan being there in an expansion. Those are really cool! It looks a bit odd at first glance but in the end is more like a Drow expansion for a surface world D&D game.