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Reported for: WooCommerce Multilingual & Multicurrency 5.1.3
Overview of the issue
When using WPML with Facebook for WooCommerce, the translated products synced to Facebook display an incorrect currency. This is due to Facebook for WooCommerce taking the currency from WooCommerce settings and not from WPML's multi-currency settings.
Workaround
Unfortunately, this is a known limitation. In order to list products in multiple currencies on Facebook, it's necessary to create multiple feeds by country/language, which Facebook for WooCommerce plugin doesn't currently support.
I don't get it. WPML says FB plugin is compatible with WPML, but it clearly isn't. How come you lure customers into paying for WPML when it's not working? Or do you mean showing random RUB prices to EUR customers and vice versa?
Unfortunately, it is a Facebook for WooCommerce limitation as explained here. For the moment, we recommend you to use the workaround here proposed.
Regards