Woocommerce currency

You can use filter “option_$option_name”.
As hardcode:

add_filter( 'option_woocommerce_currency', function($value){

  switch(wpm_get_language()) {
  	case 'en':
		$value = 'USD';
		break;
  	case 'uk':
		$value = 'UAH';
		break;
  }

  return $value;
} );

Although this question does not entirely apply to WP Multilang.