Regardless, I'm not sure if this is the best way to store language strings. You're mixing the value (say '5') with the associated language string. THis may make the string unwieldy and difficult to update.
For each product, in the products table, I'd have the value in its own field, e.g. 'available_in' storing just integers
If you're storing language strings in the ps_product_lang table, it would benefit from have a generic statement that could be used for all products using a placeholder, e.g.
content (varchar or text)
Bydd y cynnyrch hwn ar gael ymhen %d diwrnod.
This would be related to a couple of tables:
original (varchar or text)
This will be available in %d days.