Yes, I am still using High Sierra. I cannot upgrade because I have an old mac which is not supported anymore. I probably need to install Linux over it : 
I can also install the Windows version of Gramps using an emulator (Crossover). But, I need to think about the naming system fist. If I find a means to apply the system, I will install it over Crossover.
I have an older version of Reunion application which still works great. The reason I want to migrate to Gramps is because it is open source; could be options to modify to include the East African naming conversion.
Thank you guys.