Actually, both of the threads are correct. In the normal circumstances, you will not need to update the Child Theme and install the updated one and move your customization from the old child theme to the new one.
But it might be the case if the Child Theme is too old and there is a major release. If you added the Child Theme while using the version 4 of the theme then you will need to install the new version of the Child Theme by downloading it from your Themeco dashboard and move your customization to the new child theme.
If you installed the Child Theme while the theme is in version 5 then you do not need to install the Child Theme and you just need to check that the customization is correct and there are no changes in the original file of the theme.
Now regarding the issues you are experiencing, I wonder if it is related to the child theme? You can test that by activating the parent theme and see if you experience the same problems. If yes then it is not related to the Child Theme and we need to investigate more.
I suggest that you make a complete backup of your website and make sure you are using version 5.2.4 of the Theme and version 2.1.6 of the Cornerstone. If not please update them:
In case you still have issues kindly check the article below and follow the steps mentioned there: