This is a bit late. But sharing some personal observations when I encountered similar issues.
The build process fails if there is an old plugin that is not updated to work with the platform@7.0.0. At least this is the case for me. After installing this incompatible plugin, it would mess up the files in platform. After which trying to salvage the project by removing the plugin would also fail, because the files would have been put in the wrong directories when installing. You would have to remove the platform "cordova platform rm " followed by the misbehaving plugin "cordova plugin rm " and re-add back your platform before the the build can fixed.
Why android@6.30 and android@6.4.0 may work is because it is probably using the older platform project directory layout, where it appeared to use the top level /platforms/android directory for 'res' and 'libs' folder.
From android@7.0.0 onward, I notice it added the 'app' subdirectory, and your 'config.xml' and 'res' are expected at '/platforms/android/app/src/main/res/xml/config.xml' and not '/platforms/android/res/xml/config.xml'.
Older plugin may have installation/removal scripts that copy the files to the wrong places.
The only 2 ways to fix this problem is to update the plugin or downgrade the platform as suggested by Bharat Biswal.
If anyone has a more definite answer, that would be great.