You wouldn’t need to manually do anything to your categories.
You could just do this:
add_action( 'wp', function() {
if ( is_category() ) {
remove_action( 'generate_archive_title', 'generate_archive_title' );
add_action( 'generate_archive_title', 'tu_custom_archive_title' );
add_action( 'generate_after_main_content', 'tu_custom_archive_description' );
}
} );
function tu_custom_archive_title() {
?>
<div class="page-header">
<h1 class="page-title">
<?php the_archive_title(); ?>
</h1>
</div>
<?php
}
function tu_custom_archive_description() {
$term_description = term_description();
if ( ! empty( $term_description ) ) {
printf( '<div class="taxonomy-description">%s</div>', $term_description ); // WPCS: XSS ok, sanitization ok.
}
}