The JDM lights require a harness deigned for top & bottom lighting. The ej9 harness is only top lighting. So even if the JDM lights came with wiring, it STILL requires MODIFICATION of the ej9 harness.
Please note CONVERSION involves modification of YOUR vehicle to accept a non-original part except where the part is 'plug & play'.
What do you mean by this? If you fit ek9 rear lights with the wiring on the back of them and plug them into any other ek hatch they will work just the same as the ek9 no modification needed