Seeking replacement for outdated search plugin

Hi folks,

I would like to find a replacement for a plugin that is not being maintained and doesn’t work with the newest version of WordPress.

Name: Ultimate WP Query Search Filter

Self-description: This plugin let you using wp_query to filter taxonomy, custom meta and post type as search result.

The URL associated with this post is for a page on my staging site, where the plugin still works because I have not updated WP.

On the page, the plugin I wish to replace relates to the bottom form, which is a drop-down list made by the plugin from a custom taxonomy called [fe_author].

Selecting a name on the list and pressing the Go button gives search results for articles written by that author.

The plugin uses a shortcode to provide the search form and access the default WP Search page for results.

I have tried many plugins available through the Add New section of my WP Admin dashboard, but none of them seem capable of giving a drop-down list that can drive a search query.

I would be very grateful if one of you could help me find a new way to query a list of authors related to articles on the site.

The page I need help with: [log in to see the link]