You have excellent software design skills. A rare find in the software development industry. Five minutes with this plugin and I saw the following:
Consistent comments, consistent whitespace, readable code, a limited potential attack surface, code is self-contained with defenses against possible naming conflicts with other plugins, plenty of hooks, good multilingual support, and a pretty good understanding of WP's internals.
I vet and manage the deployment of all plugins for use on our multisite WP install and, until today, I had yet to find a WP plugin that met my criteria of good software design without complaints. I outright reject about half of the plugins I vet and usually end up modifying the rest. I rarely give compliments and I'm almost never impressed.
Simply put - you've got skills and I'm impressed.