Unfortunately in 4.3 we still do not support multi lingual sites. We have plans to implement this feature somewhere in the future, but I cannot promise you a specific date. Apologies for the inconvenience.
We already released an internal build that supports multi lingual migration. Please check your client profile files for it and try it. Let us know if this version works for you.
As I mentioned in my previous reply we already released this version - here is the official forum thread that is updated every time a new internal build is released -
I believe we already released the internal build that handles the multi lingual migration. You should see this build in your downloads section in your client profile. I think this build will be the last major update to the migration module, which of course will be included in the upcoming Sitefinity 5.0 release.