I don’t know what exactly he means by “for the valve in the idle to the light compatible.” But, if he disconnected the battery while working on the EGR system, he might be referring to the car’s computer relearning its idle and fuel trim strategy, which usually gets erased when power is disconnected. It erases data from memory.
Also, do you know if he cleared any trouble codes from the computer memory after replacing the valve? If not, you can go to a local auto parts store and ask them to pull any trouble codes (so that you can verify the code relates to the EGR system) and have them clear the memory. This could help. Also, you can wait for the computer to relearn the strategy, which may take a few miles. Or you can check your vehicle repair manual and see if it gives you the procedure to perform the idle relearn process.