The script make a lot of assumption that do no work so well when it is executed on a NixOS server:
+ sources/src/utils/analyse_language_files.pl sources/
usage: analyse_language_file.pl [-s]
-s: silent mode
-v: verbose mode, listing unused keys
*** Reading Source Code
*** Reading Tab files
sh: /bin/ls: No such file or directory
Report:
*******
3984 getText() calls
2252 unique keys
1 special keys