Glad you learnt it, many people use outdated software because it works, but just because it works doesn't mean its Secure or Fast (or atleast achieve its potential).
OFT: This code is better than that of the original CMS but you're still using global to get information and this is outdated.
ONT: Great CMS, just needs more OOP and yes also php-fig would help for sure! and cPanel is supported, tested with little edit!