Hi,

        intltool-merge filter the copyright line in xml.

For example, the orig file is:
https://sources.debian.org/src/stardict/3.0.7+git20210701.96b96d8+dfsg-2/dict/data/stardict.appdata.xml.in/#L2

After run:

LC_ALL=C /usr/bin/intltool-merge  -x -u -c ../po/.intltool-merge-cache ../po
stardict.appdata.xml.in stardict.appdata.xml
Found cached translation database
Merging translations into stardict.appdata.xml.
CREATED stardict.appdata.xml

The output file stardict.appdata.xml has not copyright line:

<!-- Copyright 2015 Hu Zheng <huzheng001@gmail.com> -->


The Copyright line need to reserve, otherwise, there are following errors:

appstream-util validate-strict stardict.appdata.xml
stardict.appdata.xml:
FAILED:
• value-missing         : <!-- Copyright [year] [name] --> is not present
• tag-missing           : <release> required
Validation of files failed


Thanks!