Develop face detect (trackin) for a Cordova Android app

General information for the business: We develop apps for advertising
Kind of development: Customization of existing program
Description of every module: Introduction:

I'am working on an Android (hybrid) app working with Cordova. The app itself is just a carousel/slider of images which so far works pretty well. However, I want the carousel to start when the camera of the tablet detects a person face in front of it (without the user being aware of the detection, so without camera preview).

In order to do this, I've followed the tutorial made by Blundell (http://blog.blundellapps.co.uk/tut-front-camera-face-detection-explained/) which performs face detection in the background and tried to "fusion" the resulting app (which you can download from this Github -> https://github.com/blundell/FaceDetectionTutorial) with my own Cordova app.

So far, I've managed to detect a face and display a Toast on top of my carousel, however, there seems to be some buffering issue (what I see from the logcat) and the camera stops working and so the face tracking (problem with the UI Thread ? don't know).
Description of requirements/functionality: The works:

-Implement on my Cordova app a face tracking capability that runs in the background using google API Camera2 (without camera preview).
-The face tracking must be launched once the application starts, and the detection shall repeat one time per minute and last 10 seconds, and repeat every minute while the app is open.
-Depending on the result of the detection a simple string ("face detected" / "No face detected") or boolean shall be sent to the Javascript so I can interact with my Cordova Webview accordingly.

To download my cordova app please go to :
https://www.dropbox.com/sh/qb9m4ec37p3imp2/AADbjNewLgNbLxA1l68DgkM3a?dl=0
Specific technologies required: Cordova Android
Extra notes: The job is pretty urgent, I'd appreciate if it can be done in 3 to 4 days.

NOTE: No HTML is required to be done. Minimum javascript needed, just to catch the face tracking response. No coding to activate the carousel needed.

NOTE2: If required, you can download my app as it is via this link (the file seems heavy due to several builds made via the Android Studio and the images of the carousel)