A Wordpress plugin that renames the Featured Image metabox and text.

wp-rename-set-featured-image

<?php

/**
 * Plugin Name: WP Rename Featured Image
 * Plugin URI: http://www.briannadeleasa.com
 * Version: 1.0.0
 * Author: Brianna Deleasa
 * Description: Allows the user to rename the 'Set Featured Image' text and the 'Featured Image' metabox.
 */

add_action('admin_head-post-new.php', 'wp_rename_featured_image_admin_head');
add_action('admin_head-post.php', 'wp_rename_featured_image_admin_head');
function wp_rename_featured_image_admin_head( $content ) {

    if ( 'post' !== $GLOBALS['post_type'] ) {
        return $content;
    }

    add_filter( 'admin_post_thumbnail_html', 'wp_rename_featured_image_post_thumbnail_html' );
    add_filter( 'gettext', 'wp_rename_featured_image_rename_use_as', 9999, 4 );

}


/**
 * Renames 'Use as featured image' for our post type
 *
 * @param $translation
 * @param $text
 * @param $domain
 * @return mixed
 *
 * @since 1.0.0
 */
function wp_rename_featured_image_rename_use_as( $translation, $text, $domain ) {

    $translations = &get_translations_for_domain( $domain );

    if ( $text == 'Use as featured image' ) {
        return $translations->translate( 'Use as post image' );
    }

    return $translation;

}


add_filter( 'media_view_strings', 'wp_rename_featured_image_change_featured_image_media_strings', 10, 2);
/**
 * Renames the 'Set featured image' button in the Media Library dialog window.
 *
 * @param $strings
 * @param $post
 * @return mixed
 *
 * @since 1.0.0
 */
function wp_rename_featured_image_change_featured_image_media_strings( $strings, $post ){

    if ( $post->post_type !== 'post' ) {
        return $strings;
    }

    $strings['setFeaturedImage'] = __('Set post image', 'feat-img-custom');
    $strings['setFeaturedImageTitle'] = __('Set post image', 'feat-img-custom');

    return $strings;

}


/**
 * If the current page is a 'post', rename the featured image text.
 *
 * @param $content
 * @return mixed
 *
 * @since 1.0.0
 */
function wp_rename_featured_image_post_thumbnail_html( $content ) {

    global $current_screen;

    if( $current_screen->post_type !== 'post' ) {
        return $content;
    }

    $content = str_replace( __( 'Set featured image' ), __( 'Upload Post Image' ), $content);
    $content = str_replace( __( 'Remove featured image' ), __( 'Remove Post Image' ), $content);

    return $content;

}


add_action( 'do_meta_boxes', 'wp_rename_featured_image_do_meta_boxes' );
/**
 * Rename the 'Featured Image' metabox.
 *
 * @param none
 * @return none
 *
 * @since 1.0.0
 */
function wp_rename_featured_image_do_meta_boxes() {

    remove_meta_box( 'postimagediv', 'post', 'side' );
    add_meta_box( 'postimagediv', __('Post Image'), 'post_thumbnail_meta_box', 'post', 'normal', 'high' );

}

Hello ,
Good work 👍

This block
function wp_rename_featured_image_post_thumbnail_html( $content ) {
global $current_screen;
if( $current_screen->post_type !== 'post' ) {
return $content;
}
$content = str_replace( __( 'Set featured image' ), __( 'Upload Post Image' ), $content);
$content = str_replace( __( 'Remove featured image' ), __( 'Remove Post Image' ), $content);
return $content;
}
add_action( 'do_meta_boxes', 'wp_rename_featured_image_do_meta_boxes' );

On my case custom_post_type will replace only "Set featured image"
But replacing "Remove featured image" link will not work ...

and I would recommend this block for editing both

// Rename the featured image text.
function rename_set_featured_image( $content ) {
return $content = str_replace( __( 'Set featured image' ), __( 'Set product logo' ), $content );
}
add_filter( 'admin_post_thumbnail_html', 'rename_set_featured_image' );

// Rename the Remove featured image text.
function rename_remove_featured_image( $content ) {
return str_replace( 'Remove featured image', 'Remove product logo', $content );
}
add_filter( 'admin_post_thumbnail_html', 'rename_remove_featured_image', 9999, 1 );

Thank you