It is impossible put strings automatically back to upstream. You never knows, which change makes strings worse and which change makes strings better. Import back to upstream always requires native language knowledge and communication with the upstream community. Automatic tool can only collect string changes and additions and create nice review files. No automatic tool can identify better string in case of difference. It must be reviewed by human. po-review actually does not actually compare LCN and upstream, but downstream package and upstream. The comparison of LCN and upstream can be done in the same way, but it is not yet implemented. Stanislav Brabec