corrected parsing joined with unC0Rr's corrected generating finally gives the right result
#!/bin/sh -
# Script to update all frontend locale files.
# HOW TO USE:
# - Run this script in the tools/ directory.
# Result: All .ts files in share/hedgewars/Data/Locale will be updated.
lupdate ../QTfrontend -ts ../share/hedgewars/Data/Locale/hedgewars_*.ts