I don't think it changes the underlying role and grade structure - it's only about changing the job title. Doesn't really affect anything other than your email footer.

It's actually the sort of thing that used to be common in small tech companies in the pre-dot com era. There'd be a budget for having business cards printed up, and people would get to call themself things like "Intrepid C++ Wizard", but from the point of view of the org chart / HR / payroll that they'd just be a senior member of the engineering team.