How to set the Organic Group while saving a node based on the node's current language
Using Rules, you can add an event for when a new node is saved, add conditions for both content type and language and then use an action for assigning the OG's nid to the og_group_ref field.

Use set a data value if cardinality of the node is set to 1 or add to list for more than 1.

Without rules or code, I would have a new node link in each organic group and prepopulate the language and og_group_ref fields.