The scheduler changes the node's language to default-language while publishing.
This happens if the scheduler is run by drupal's cron (called by system-cron or manually) and scheduler's lightweight cron (called by system-cron), but if i start the scheduler's lightweight cron manually by admin-interface it's published with the correct language settings...
It happens on both, single nodes and on translated nodes.
I tried for hours with different settings and configurations. The problem occurs on 2 big sites (with 3 languages), but not on 1 low-level site (with 2 languages).