Hi
Interesting that this doesn't handle multi-language. I understand your frustration. In my case, the problem was that it wouldn't update the feature on CSV import, it would keep on adding values to it.
Hence the 'solution' above that effectively nukes the product features every time there is an import and replaces the features with the new ones specified in the CSV import.
Impact on multi-lang wasn't even a thought...
I guess my question to you is: is the reason you were looking at this post because you were using the free module "Advanced Feature values" as above?
Because the reason the CSV import would add and not replace feature values is because of the functionality added by this module.
If you're not using this module, then the modifications above are not necessary - and could possibly cause unnecessary headaches.
Anyway, I know this is an older post, just thought I'd provide some feedback.