That library is too old :((

From Changelog:
(30 June 2017) [Linux only]
libpng12 was bundled for improved compatibility with newer Linux distros (Ubuntu 16.10 or newer)

Currently (Xubuntu 22.04 LTS and Xubuntu 23.10) use libpng16.
So -> the installed game would not run unless I I cast magic with a tambourine.. by introducing that old crap libpng12 into my OS.

Curious, if they bundled that stuff - is it possible to detach it from the Linux installer now? :)
Since it is not relevant anymore.

If you mean the Dosbox using Colonization, that's a W/E, use your own Dosbox, I personally prefer the staging spin.