E-learning platform in Codeigniter 3

We are a company providing educational services on the basis of e-learning courses. They are conducted on our dedicated platform, made by an external contractor - we are looking for a programmer who, working as part of a team, will be able to audit it, propose possible improvements and, after preparing and accepting the quote, implement the postulated changes.

The system is based on Codeigniter 3 code in php, javascript, bootstrap. It includes several types of accounts (superadmin, admin, teacher, student) that interact with each other such as asking questions, sending assignments to be checked, commenting on solutions, commenting on the operation of the system, etc.

The platform is used during peak periods by up to several thousand people per day, generally it is a couple of hundred people each day, it is located on the Cyberfolks server.