The end result of any 'translation/migration', the SKU's of translated products/variants should be the same as the products/variants of the original language. A product/variant must have the same SKU - no matter what language the web shop are using. This is quite fundamental in business/shopping.
If you look at a translated variant (in your test environment), the value of the SKU is taken from the product (not the variant) of the original language, which is wrong. See attachment.
If we still need to put in unique SKU's in the translated CSV, then your import/export function mixes up the SKU's - ie. it should copy the SKU from the variant of the original language, not the product.
and again, I have successfully performed such imports before with the same SKU's in translated CSV's. You can see that I have another support ticket - here we also did the same without such issues. We had no problems importing the products/variants, but the wpml import/export function mixes up the categories, which is why I have the other support ticket (which is still active). I think that 'something else' has changed, since we now can't import translations with identical SKU's. It could be changes in Woocommerce or changes elsewhere in WPML.
