Line items do not utilize translated titles

What you've described is expected behavior to me, but I do have a follow-up question: are you translating product titles at all?

The issue here is that the Add to Cart form connects the resultant line item to its display context, which in your case is language specific. I ask the follow-up question, because I don't know if it would actually use a French product title if you were translating to French and the site was being viewed in that language.

I am having exact same issue, all translations for product display work great except the title of the product in shopping cart. Has anyone found a solution to the problem?

Actually, I have not been able to find how to add translation to the product itself, only the display product, so when added to shopping cart there is no translation. So how to add translation to product types?

We have Commerce products and multiple Products displays (for each language a node).

The title in the shopping cart is not correct for the current language (at the moment the product is added to the cart).

I found function 'commerce_product_line_item_title' in commerce/modules/product_reference/commerce_product_reference.module.

/**
 * Returns an appropriate title for this line item.
 */
function commerce_product_line_item_title($line_item) {
  // Currently, just return the product's title.  However, in the future replace
  // this with the product preview build mode.
  if ($product = entity_metadata_wrapper('commerce_line_item', $line_item)->commerce_product->value()) {
    return check_plain($product->title);
  }
}

In the 'line_item' object there is a entity reference in [data] [context] [entity]
We have the entity_type and the entity_id. Is it possible to load the title of that entity? This would solve the problem for me. How can I overwrite 'commerce_product_line_item_title'

We have also a problem in 'commerce_cart_rules_add_to_cart_message'. The title of the product is not correct in this function:

/**
 * Rules action: displays a the default translatable Add to Cart message.
 */
function commerce_cart_rules_add_to_cart_message($product) {
  drupal_set_message(t('%title added to <a href="!cart-url">your cart</a>.', array('%title' => $product->title, '!cart-url' => url('cart'))));
}

The 'product' object has the wrong title. How can we overwrite this function?

Yep i can conform that #8 is working:

You need to set 2 relations:

1.) Set a relation to: (Line Item) Commerce Line item: Product
2.) Commerce Product: Node referencing products from field_product

I needed to disable sql rewrite in query settings too since that one views bug when setting relations between products and product 'nodes'

I could see something like that going in but not as written. We already have in the line item the display context for the product, so there's really no reason to make a blind load of the node like that.

There are three approaches to tackle this issue (C is the best, in my case).

A) Enable Commerce Backoffice Product, and use content translation for nodes and completely disparate variations per product language.

B) Disable Commerce Backoffice Product (if using Commerce Kickstart at all), so variation types are cancelled and the product type can have "Entity Translation" enabled, as is suggested here.

C) Enable Commerce Backoffice Product with #2203317: Support Entity Translation for Commerce Product and use a single node and Entity Translation enabled variation types. Apply #2203383: Pass user langauge to entity_view() in Rendered product formatter so the rendered product displayed in the "Shoping Car Form" view will get translated. Enable entity translation (field-level translation) for both the product display node and the variation types used. The product reference field should not be translateable.

For approaches A & C:

1. Apply the patch #1545896: Add Entity Translation integration for the Inline Entity Form module and get latest dev version of Entity Translation, to include #1865244: Allow multiple translation handlers on the same form.

For A:

1. Configure the product content type multilingual support as Enabled, with translation (the multiple nodes approach).
2. In your product content type's product reference field (field_product in the "Product display" content type) mark "Users may translate all occurrences of this field". This is necessary so after the first save, clicking "Translation" will open the translation form with no variation types already in the form, so they have to be filled for each language anew and not synchronized across translations.

As far as I saw, commerce_product_line_item_title() is called but has no effect on the display of the cart, at least not with the Commerce Kickstart default configuration. The title that is eventually displayed in the cart is the product variation's title, through the "Rendered product" formatter. #2203383: Pass user langauge to entity_view() in Rendered product formatter fixes this formatter.

Patch #10 helped me out translating the product titles in the 'add to cart' mesage, thanks! (Drupal Commerce 7.x-1.11 / 2015-01-16)

Hi there!
Thanks for the Patch.
Now a Notice pops up

Notice: Only variables should be passed by reference в функции commerce_cart_rules_add_to_cart_message() (строка 209 в файле /commerce/modules/cart/commerce_cart.rules.inc).

i did a tiny change in the patch to fix this

With Automatic Entity Label module title field in product variation could be customized and also it will be auto-translatable. In my commerce kickstart site, I checked "Automatically generate the label and hide the label field" under "Auto label" tab of my product variation and used [commerce-product:field-product-node:0:title] as Pattern for the title.
In shopping cart form views "Commerce Line Item: Title" is selected for displaying auto-translated title.
By this approach add to cart message is also translated.
Don't forget to uncheck "Auto generate the product title" in field_product of product content type.