Generally an engine will encounter issues with reciprocating weight and getting enough fuel and air before it starts seeing issues with reaching the speed of the flame front. Racing engines have different requirements than road engines that allow different construction methods to reach higher RPM.

They can use lighter and possibly more expensive internals. This is bad for road engines because they have a lower lifetime and are more expensive to fix, but fine for racing cause they rebuild engines often. There's also more advanced valves operated pneumatically or electrically that maximize their open duration and minimize the time it takes to open or close them. Again these are more expensive to maintain, which is fine for racing but bad for road vehicles.

ELI5 summary: throwing more money at specific engine components can increase redline, but doing so is bad for regular car engines due to maintenance costs and reliability

I'm not familiar with that particular engine, but an example of a road diesel engine that has a redline above 5k RPM is the Mercedes OM606. It has dual overhead cams and pistons with a larger bore than stroke, which isn't the norm for diesels.