Comment # 5 on bug 1127885 from Lukas Ocilka

I think that the "problem" is this:

During an installation, you can choose a different language and the installer
switches to that "immediately". In fact, it needs to download the language
from installation media, extend the inst-sys, switch the language and then
redraw the UI.

During firstboot we may have some languages installed, but mostly is just one
language - the one which the module starts with. When you switch the language,
firstboot needs to initialize repositories (if not done yet), run solver to 
select appropriate packages for the language, install those packages, switch
the language and then redraw the UI.

So what could potentially break?
- Repos were not available
- Firstboot requested some language, but packages were not available
- Solver found a conflict (and did not report it)
- Packager was not able to install those packages
- RPM error
- ...