should I replace wct-istanbul by WCT-istanbub in order to estimate how much polymer web compnents is test coveraged

Question

There is some similiarity between my question and How to measure common coverage for Polymer components + .js files?. Nevertheless, it is accepted as answer "split to .js files and include it to components" in order to use wct-istanbul and all my web components and tests are in .html files (the javascript is inside of each .html file).

My straight question is: can I still use wct-istambul to check how much from my code is covered by tests? If so, what is wrong in configuration described bellow? If not, is wct-istanbub planned to replace wct-istanbul for polymer projects?

package.json

"polyserve": "^0.18.0",
"web-component-tester": "^6.0.0",
"web-component-tester-istanbul": "^0.10.0",

...

wct.conf.js

var path = require('path');

var ret = {
    'suites': ['test'],
    'webserver': {
        'pathMappings': []
    },
    'plugins': {
        'local': {
            'browsers': ['chrome']
        },
        'sauce': {
            'disabled': true
        },
        "istanbul": {
            "dir": "./coverage",
            "reporters": ["text-summary", "lcov"],
            "include": [
                "/*.html"
            ],
            "exclude": [
            ],
            thresholds: {
              global: {
                statements: 100
              }
            }
        }
    }
};

var mapping = {};
var rootPath = (__dirname).split(path.sep).slice(-1)[0];

mapping['/components/' + rootPath + '/bower_components'] = 'bower_components';

ret.webserver.pathMappings.push(mapping);

module.exports = ret;

Well, I tried WCT-istanbub (https://github.com/Bubbit/wct-istanbub) which seams to be a temporary workaround (Code coverage of Polymer Application with WCT), it works.

wct.conf.js

        "istanbub": {
            "dir": "./coverage",
            "reporters": ["text-summary", "lcov"],
            "include": [
                "**/*.html"
            ],
            "exclude": [
              "**/test/**",
              "*/*.js"
            ],
            thresholds: {
              global: {
                statements: 100
              }
            }
        }
...

and the result is ... chrome 66 RESPONSE quit() chrome 66 BrowserRunner complete Test run ended with great success

chrome 66 (2/0/0)

=============================== Coverage summary ===============================
Statements   : 21.18% ( 2011/9495 )
Branches     : 15.15% ( 933/6160 )
Functions    : 18.08% ( 367/2030 )
Lines        : 21.14% ( 2001/9464 )
================================================================================
Coverage for statements (21.18%) does not meet configured threshold (100%)




Error: Coverage failed