@radokristof sorry for late answer, I completely missed this topic. For those who still had this issue:
I just installed the fonts with

sudo apt-get update
sudo apt-get install fonts-roboto

then

fc-cache -fv
pm2 restart MagicMirror

and voila… works for me.

@maros Did you fix this issue? I’ve encountered the same with Polish news…

edit:
solved by installing Roboto fonts into Raspbian (found somewhere here at the forum or in the Internet).