This feature is only recommended for use with macOS 10.7 through 10.8. As of macOS 10.9, EagleFiler supports Finder tags, which are indexed by Spotlight and are much faster than copying tags to Spotlight comments.
If this is checked, EagleFiler will set the Spotlight comments for each file to the names of the tags that it’s been assigned. This enables you to search for a file using Spotlight by typing tag names as part of the query. Any existing comments will be lost. If this is not checked, EagleFiler will preserve the existing Spotlight comments when importing files.
EagleFiler will automatically copy the tags to the comments when a library is opened and periodically thereafter. You can force it to update the comments by using the Backup Metadata command.
There is an esoteric preference to control the tag prefix that’s added to each tag name in the comments. The default prefix is “&”.