Yeah this stuff is great, but it works only with 32bit devices, on iphone 5s and newer, wkwebview will fallback to uiwebview, so, waiting for a next release.
Yes, you are right. The WKWebView has a bug running on 64 bit devices within a 32 bit app. We are already working on adding 64 bit compilations to CocoonJS, so the WKWebView will soon be available on 64 bit devices.
About removing the Splash, you can contact our sales team at sales[at]ludei.com and they will help you. Right now it is the only information I can provide you. However, I can tell you we are listening to your demands and we will take them into account.