1. How would you change it?
2. Where/how can we read the description currently?

It is a simple reminder when the bug 119551 will be fixed, since the current description of the LibreOffice’s command line argument “--infilter” does not help sufficiently. Also, for example you should replace the current examples for this argument by a template syntax and a link to the webpage which will contain the details.
You can read the description through the following command—from Windows:
soffice.exe --help

Now it displays:
   --infilter={filter} Force an input filter type if possible. For example:    
                       --infilter="Calc Office Open XML"                     
                       --infilter="Text (encoded):UTF8,LF,,," 
quite explicit.
If disagree, please explain why.
Meanwhile, let's put this one to WFM.