It looks absolutely awful using 5.3.1.2 on Ubuntu 17.04:
Do you have Calibri on your Ubuntu? Do you have a reference screenshot of how it is expected to look? Do you have to use exactly that old version of 5.3 branch (and so we don’t know if a latter bugfix version could have fixed your issue)? What rendering do you use (OpenGL e.g.)?
You can install Carlito font from Google which is designed to match Calibri
Carlito in installed with LibreOffice itself since 4.4
If I am not wrong Carlito is not installed by Ubuntu by default. My PC is under Ubuntu and I installed its ttf file in ~/.fonts because Carlito was not installed and I was not aware there is package for it.