Translate only terms from taxonomy "contact_area" when filterin "contact" post type posts. Posts are not translates at all because they only have name, email, and phone number.

translate-only-terms.php

<?php
$terms = get_terms( array(
	'taxonomy'   => 'contact_area',
	'hide_empty' => false, // Other than default language don't have any posts.
	'orderby'    => 'name',
	'lang'       => function_exists( 'pll_current_language' ) ? pll_current_language() : '',
) );

if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) :
	foreach ( $terms as $term ) :
		// Always use default language ID because we don't have translations for other languages.
		$term_default_lan_id = function_exists( 'pll_get_term' ) ? pll_get_term( $term->term_id, pll_default_language() ) : $term->term_id;
		echo '<option value="' . $term_default_lan_id . '"' . selected( $term->slug, 'hallinto', false ) . '>' . $term->name . '</option>';
	endforeach;
endif; ?>