R4 should imo be doing ERC2.

Just to separate them from the start.

Then you will get logic, with ERC topclass R5, being one below WRC.

In 2019 WRC, R4 should be the next WRC3 level, and R2 being JWRC.

Level WRC Regional
1 WRCar R5
2 R5 R4
3 R4 R2
4 R2