Get Spotlight to search in Caskroom subdirs (which is now in /usr/local/)
I found the answer provided by user vitorgalvao on the project's Github page: https://github.com/caskroom/homebrew-cask/issues/22317


  Spotlight doesn’t index /usr/local/, that why we started using /opt in the first place. Reinstall your apps with --force and they’ll be moved (our new behaviour). Spotlight will see them then.