My improvements:

Now the baseSrc parameter allows entering an array. This way, you could add angular multi-project projects, just by setting all the directories of the different projects:

killTranslateZombies({
  translateFilePath: 'C:\\plastic\\auditmap-pipeline-webhosting\\mapfre-auditlib\\src\\assets\\i18n\\es.json',
  baseSrc: [
    'first-application/src',
    'libraries-project/src' ]
});

Added an alreadyVerified option to avoid the reporting of zombie keys that have been already verified and are correct. This is an attempt to mitigate the problems found with dynamic keys: if you mark certain keys as "verified", those will not be reported as zombies anymore.

killTranslateZombies({
  [...]
  alreadyVerified: [
  	'this.key.is.not.a.zombie',
  	'this.other.key.is.not.a.zombie'
  ]
});

List of zombie keys can be exported, too (see below). This way, when you want just to check your precious translate file and check, line by line, the translations found and remove manually those that are zombies, you can make that too, just asking
the function to write down the list of zombie keys it have found:

killTranslateZombies({
  translateFilePath: 'C:\\plastic\\auditmap-pipeline-webhosting\\mapfre-auditlib\\src\\assets\\i18n\\es.json',
  baseSrc: [
    'first-application/src',
    'libraries-project/src' ],
  exportZombieKeys: 'found-zombie-keys.json', 
  alreadyVerified: [
  	'this.key.is.not.a.zombie',
  	'this.other.key.is.not.a.zombie'
  ]
});

Function walkThroughAllFiles is not that complicated, in my humble opinion. Check out the new version.

Other functions have been changed name: findInFile in fact, does not just "find in a file" the zombie keys, but remove the found keys, so it's changed to removeKeyIfFoundInFile.

Libraries under package.json have been upgraded. I've done my best to preserve functionality of the existing scripts, but
I failed in some cases due to errors in libraries (trash).