Custom term meta fields

To solve custom meta fields quickly you can add an hook inside terms-edit-form.php

do_action( "sublanguage_{$taxonomy}_edit_form_fields", $tag, $taxonomy, $language );

Here is an example for use

<?php

function translation_custom_taxonomy_fields( $term, $taxonomy, $language ){

	global $sublanguage;

	// archive title
	$meta_value = $sublanguage->translate_term_meta( $term, 'archive_title', true, $language, '' );
	?>
	<tr class="form-field">
		<th scope="row" valign="top">
			<label for="archive-title"><?= __('Archive title', DFHR) ?>:</label>
		</th>
		<td>
			<input type="text" name="sublanguage_term[<?php echo $taxonomy; ?>][<?php echo $language->ID; ?>][archive_title]" id="archive-title" value="<?php echo $meta_value; ?>" />
			<p class="description"><?= __('Add page archive title.', DFHR) ?></p>
		</td>
	</tr>

	<?php
}

add_action("sublanguage_{$tax}_edit_form_fields", "translation_custom_taxonomy_fields", 20, 3 );