SF_10.1, SF_10.2, SF_11.0, SF_11.1, SF_11.2, SF_12.0, SF_12.1, SF_12.2, SF_13.0 - https://docs.sitefinity.com/for-developers-add-a-translation-to-a-localized-product

TranslalteProduct.cs

using System;
using System.Globalization;
using System.Linq;
using System.Text.RegularExpressions;
using Telerik.Sitefinity.Ecommerce.Catalog.Model;
using Telerik.Sitefinity.Model;
using Telerik.Sitefinity.Modules.Ecommerce.Catalog;

namespace Telerik.Sitefinity.Documentation.CodeSnippets.DevGuide.SitefinityEssentials.Multilingual
{
    public partial class MultilingualSnippets
    {
        public static void TranslateProduct(Guid productId, string title, string description, string targetCulture)
        {
            CultureInfo culture = CultureInfo.GetCultureInfo(targetCulture);

            CatalogManager catalogManager = CatalogManager.GetManager();
            Product product = catalogManager.GetProduct(productId);

            if (product != null)
            {
                product.Title.SetString(culture, title);
                product.GetString("Description").SetString(culture, description);
                product.UrlName.SetString(culture, Regex.Replace(title.ToLower(), @"[^\w\-\!\$\'\(\)\=\@\d_]+", "-"));
                catalogManager.Provider.RecompileItemUrls(product);

                catalogManager.SaveChanges();
            }
        }
    }
}