Downloadable file URLs may be overwritten when editing translated products directly

Overview of the issue

There is a setting at WooCommerce > WCML > Settings for downloadable products that enables downloading different files with translations of products, but if you directly edit a translated product the file may be reset to that of the default language.

Workaround

The setting can be overridden at the individual product level when editing the default language product, but if you still experience problems you can edit the file wp-content/plugins/woocommerce-multilingual/classes/Synchronization/Component/DownloadableFiles.php

Locate this if condition (from line 33):

		if (
			$customProductSync === WCML_Downloadable_Products::SYNC_MODE_META_SELF
			|| ( ! $customProductSync && ! $generalProductSync)
		) {

and replace it with

		if ( 
			$customProductSync === WCML_Downloadable_Products::SYNC_MODE_META_AUTO ||
			( $customProductSync !== WCML_Downloadable_Products::SYNC_MODE_META_SELF && $generalProductSync )		
		) {