The category substitute words are not being indexed, so using them in the search does not bring products within the corresponding category.

1. Enter a substitute word for a given category.
2. Make sure that your products are indexed after the update.
3. Search for products using that substitute word in the store.

Register the substitute words directly in the products of the category. Or, if it's the case, create a redirect 301 of this substitute word for the category that should be returned.