macOS – Identify Folders and Files in Library Folder

Spotlight is already indexing those files and folders. You can check for the file names.

The actual problem is that the importer is ignoring the "code" portion of the files so the strings you want to find are not matching.

mdfind -name fmwebd_home.html

If you copy a html file to your desktop, you can play with editing them to include strings inside the body of the html - and see if spotlight can find things. Junk names like ZZtestZZ are easy to make up that don't return other spotlight matches.

mdfind  -interpret ZZtestZZ

Also, if you search in Spotlight graphically, you might want to save smart folders/searches that include the system files since they are normally suppressed from default searches.

It is not possible to search for folders by file size. The combined size of all files and folders contained in a folder is computed on the fly by Finder when you ask for it.

For normal Finder windows, you can enable the option to “Calculate all sizes” in View > View Options. That option is not available for search results.

What you can do is search for files that were recently added to the system and then check the total size of folders where such a files were found. While the file you find using this method may be small, it can be part of a larger collection of files you have downloaded or installed.

I have written a blog post that shows how to find large files and folders. In the blog post I use HoudahSpot. Full disclosure: I am the developer of HoudahSpot.

You can use much the same techniques with Finder. HoudahSpot however makes it easier to set up the search. It also has the ability to show the “total size” of folders as a column in search results. You can also use HoudahSpot to quickly compute the total size of a folder.

Both Finder and HoudahSpot search the Spotlight index. Neither will be able to find system files. Yet HoudahSpot will come up with search results that the Finder intentionally hides.

BTW, if disk space "went missing” just recently, try restarting your Mac. This will clean up temporary files left behind by applications.