Modeewine

<h4>What is «Polylang Theme Strings» and what for is it?</h4>
This plugin gives additional features to the plugin Polylang. It automatically scans all templates files and scripts of the active WP theme (and all plugins) for available strings that can be translated. For example:
<ul>
<li><code>pll__('...');</code></li>
<li><code>pll_e('...');</code></li>
</ul>
and adds them to the Polylang registery, after what you can manage the translation of finded strings using the administration panel. It will make your life easier for the development of multilanguage’s projects, because you will not need to enter the needed strings to translate manually – the plugin will do all the work for you. 
Don’t forget that in the example are described the PHP-function calls, that is why they have to be inside of PHP-tags.
<h4>How works «Polylang Theme Strings»?</h4>
You have to install the plugins «Polylang» and «Polylang Theme Strings» on your multilanguage WordPress CMS project and they must be both active. When you are in the settings of plugin (Polylang) in the tab «Strings translation» the «Polylang Theme Strings» scans automatically the active theme of your project, find all the code strings that needed to be translated, adds them to the register, displays them on that page and gives to user the ability to translate these strings.
Like you can see, the «Polylang Theme Strings» is perfectly integrate with the «Polylang» plugin and works in automatically mode – it is comfortable, simple, and useful!
From version 4.0 «Polylang Theme Strings» got settings page where you can configure the search strings-translations more deeply.
Learn more in <a href="http://modeewine.com/en-polylang-theme-strings" rel="nofollow ugc">http://modeewine.com/en-polylang-theme-strings</a>.

Polylang Theme Strings

I think there is a bug and it is changing the site language to english.

Works fine

Automatic scanning of strings translation in the theme and registration of them in Polylang plugin. Extension for Polylang plugin.

JS Morisset

Google Merchant product and inventory feed XML for WooCommerce and custom product pages, including multilingual support.
E-Commerce Plugin Optional:
WooCommerce is suggested but not required – the WPSSO Google Merchant Feed XML add-on can also use product information from custom product pages.
Complete WooCommerce Support:
WooCommerce simple products, product variations, product attributes, product meta data, and custom fields are all fully supported.

Automatic Multilingual Support:
The Google merchant product feed XMLs are automatically created in your site’s language(s) from Polylang, qTranslate-XT, WPML, or the installed WordPress languages.
After activating the WPSSO Google Merchant Feed XML add-on, see the SSO > Google Merchant settings page for your feed URLs.
Google Merchant Feed XML Attributes:
<ul>
<li>Additional image link <code>&#91;additional_image_link&#93;</code></li>
<li>Adult oriented <code>&#91;adult&#93;</code></li>
<li>Age group <code>&#91;age_group&#93;</code></li>
<li>Availability <code>&#91;availability&#93;</code></li>
<li>Brand <code>&#91;brand&#93;</code></li>
<li>Condition <code>&#91;condition&#93;</code></li>
<li>Color <code>&#91;color&#93;</code></li>
<li>Description <code>&#91;description&#93;</code></li>
<li>Energy efficiency class <code>&#91;energy_efficiency_class&#93;</code></li>
<li>Gender <code>&#91;gender&#93;</code></li>
<li>Google product category <code>&#91;google_product_category&#93;</code></li>
<li>Google search index <code>&#91;canonical_link&#93;</code></li>
<li>GTIN <code>&#91;gtin&#93;</code> (inluding UPC, EAN, and ISBN)</li>
<li>Image link <code>&#91;image_link&#93;</code></li>
<li>Item group ID <code>&#91;item_group_id&#93;</code></li>
<li>Link <code>&#91;link&#93;</code></li>
<li>Material <code>&#91;material&#93;</code></li>
<li>Maximum energy efficiency class <code>&#91;max_energy_efficiency_class&#93;</code></li>
<li>Minimum energy efficiency class <code>&#91;min_energy_efficiency_class&#93;</code></li>
<li>MPN <code>&#91;mpn&#93;</code></li>
<li>Pattern <code>&#91;pattern&#93;</code></li>
<li>Price <code>&#91;price&#93;</code></li>
<li>Product ID <code>&#91;id&#93;</code></li>
<li>Product length <code>&#91;product_length&#93;</code></li>
<li>Product height <code>&#91;product_height&#93;</code></li>
<li>Product type <code>&#91;product_type&#93;</code></li>
<li>Product weight <code>&#91;product_weight&#93;</code></li>
<li>Product width <code>&#91;product_width&#93;</code></li>
<li>Sale price <code>&#91;sale_price&#93;</code></li>
<li>Sale price effective date <code>&#91;sale_price_effective_date&#93;</code></li>
<li>Shipping <code>&#91;shipping&#93;</code>
<ul>
<li>Country <code>&#91;country&#93;</code></li>
<li>Location group name <code>&#91;location_group_name&#93;</code></li>
<li>Postal code <code>&#91;postal_code&#93;</code></li>
<li>Price <code>&#91;price&#93;</code></li>
<li>Region <code>&#91;region&#93;</code></li>
<li>Service <code>&#91;service&#93;</code></li>
<li><a href="https://wordpress.org/plugins/wpsso-wc-shipping-delivery-time/" rel="ugc">WPSSO Schema Shipping Delivery Time for WooCommerce</a> add-on required for handling and transit times:
<ul>
<li>Maximum handling time <code>&#91;max_handling_time&#93;</code></li>
<li>Minimum handling time <code>&#91;min_handling_time&#93;</code></li>
<li>Maximum transit time <code>&#91;max_transit_time&#93;</code></li>
<li>Minimum transit time <code>&#91;min_transit_time&#93;</code></li>
</ul>
</li>
</ul>
</li>
<li>Shipping length <code>&#91;shipping_length&#93;</code></li>
<li>Shipping height <code>&#91;shipping_height&#93;</code></li>
<li>Shipping weight <code>&#91;shipping_weight&#93;</code></li>
<li>Shipping width <code>&#91;shipping_width&#93;</code></li>
<li>Size <code>&#91;size&#93;</code></li>
<li>Size system <code>&#91;size_system&#93;</code></li>
<li>Size type <code>&#91;size_type&#93;</code></li>
<li>Title <code>&#91;title&#93;</code></li>
</ul>
Google Merchant Inventory XML Attributes:
<ul>
<li>GTIN <code>&#91;gtin&#93;</code></li>
<li>Merchant ID <code>&#91;target_customer_id&#93;</code></li>
<li>Price <code>&#91;price&#93;</code></li>
<li>Product ID <code>&#91;id&#93;</code></li>
<li>Quantity <code>&#91;quantity&#93;</code></li>
<li>Store code <code>&#91;store_code&#93;</code></li>
<li>Timestamp <code>&#91;timestamp&#93;</code></li>
</ul>
<h3>WPSSO Core Required</h3>
WPSSO Google Merchant Feed XML is an add-on for the <a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WPSSO Core plugin</a>, which creates extensive and complete structured data to present your content at its best for social sites and search results – no matter how URLs are shared, reshared, messaged, posted, embedded, or crawled.

WPSSO Google Merchant Feed XML

Google Merchant product and inventory feed XML for WooCommerce and custom product pages, including multilingual support.

Polylang Theme Strings vs WPSSO Google Merchant Feed XML