Not all themes are designed for microcomputers like the Pi. Some are done for modern (HT)PCs with at least a quad core CPU, 8 GB of RAM and whatnot. I’m sure I’m not the only interested in hearing your installed themes and any other graphical modifications.
Have a look at RetrOSMC, a now fully functioning RetroPie installation inside of OSMC that lets you switch between gaming with RetroPie and media centre OSMC.
The sad face emoji shouldn’t happen. Still, I think you need to work on your attitude towards open/free software. This is an ongoing project receiving several updates, at least once a month, sometimes once a week.