When pressing the webview for 500ms on iOS9 a magnification glass pops up. On UIWebView the popup is always at the top of the page (see the screenshot in the readme here: https://github.com/EddyVerbruggen/cordova-plugin-ios-longpress-fix), on WKWebView the popup is where your finger is.
On UIWebView we have yet to find a non-native way (read: CSS) to fix the problem, but on WKWebView a few lines of CSS seem to fix the issue.
This improvement is aimed at resolving the problem for UIWebView. There is no reason not to include a fix for WKWebView as well, other than I didn't invest time in it because of the CSS workaround.