WooCommerce Product Add-Ons Ultimate by pluginrepublic.com

Plugin link: https://pluginrepublic.com/wordpress-plugins/woocommerce-product-add-ons-ultimate/

In file plugins\product-extras-for-woocommerce\inc\functions-cart.php add next code:

if (class_exists('WOOCS')) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed) {
        $price = $WOOCS->woocs_exchange_value(floatval($price));
    }
}

to the same file add next code:

if (class_exists('WOOCS') AND $price) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed) {
        $currrent = $WOOCS->current_currency;
        if ($currrent != $WOOCS->default_currency) {
            $currencies = $WOOCS->get_currencies();
            $rate = $currencies[$currrent]['rate'];
            $price = $price / $rate;
        }
    }
}

to the same file add next code:

if (class_exists('WOOCS')) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed AND isset($cart_item_data['product_extras']['price_with_extras'])) {
        $currrent = $WOOCS->current_currency;
        if ($currrent != $WOOCS->default_currency) {
            $currencies = $WOOCS->get_currencies();
            $rate = $currencies[$currrent]['rate'];
            $cart_item_data['product_extras']['price_with_extras'] = $cart_item_data['product_extras']['price_with_extras'] / $rate;
        }
    }
}

to the same file file add next code:

if (class_exists('WOOCS')) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed) {
        $currrent = $WOOCS->current_currency;
        if ($currrent != $WOOCS->default_currency) {
            $currencies = $WOOCS->get_currencies();
            $rate = $currencies[$currrent]['rate'];
            $cart_item_data['product_extras']['price_with_extras_discounted'] = $cart_item_data['product_extras']['price_with_extras_discounted'] / $rate;
        }
    }
}

to the same file add next code:

if (class_exists('WOOCS') AND $item['price']) {
    global $WOOCS;

    if ($WOOCS->is_multiple_allowed) {
        $currrent = $WOOCS->current_currency;
        if ($currrent != $WOOCS->default_currency) {
            $currencies = $WOOCS->get_currencies();
            $rate = $currencies[$currrent]['rate'];
            $item['price'] = $rate * $item['price'];
        }
    }
    $item['value'] = preg_replace('/\((.+)\)/', "", $item['value']);

//$item['value'] .= sanitize_text_field("(" . wc_price($item['price']) .")");
}

o your current child wp theme file functions.php add next code:

function pewc_get_multicurrency_price($price, $item, $product) {

// Compatibility with WooCommerce multilingual
    $price = apply_filters('wcml_raw_price_amount', $price);

    if (class_exists('WOOCS')) {
        global $WOOCS;
        if ($WOOCS->is_multiple_allowed) {
            $price = $WOOCS->woocs_exchange_value(floatval($price));
        }
    }

    return $price;
}

add_filter('pewc_filter_field_price', 'pewc_get_multicurrency_price', 10, 3);
add_filter('pewc_filter_option_price', 'pewc_get_multicurrency_price', 10, 3);

Shortcodes, functions, actions and filters reference for FOX WooCommerce Currency Switcher