Run import when in the import map set Setting locale en_US.
That will add a Preferred Label lang en_US.
Run another import when in the import map set Setting locale he_IL.
The Preferred Label lang en_US will be delete and new Preferred Label lang he_IL will be add.
Where did it come from:
that came from app/models/ca_data_importers.php line 2287
$t_subject->getPreferredLabelCount() > 0
if there is any Preferred Label it delete it.
it should be $t_subject->getLabelCount(TRUE,$vn_locale_id) > 0
that is count only the Label in the current import lang
Changed to only delete labels of current import locale. This change is in the develop branch.
Tested it, working good.