Well here what you need to know about CNG on EFI
Emulator function is simple, it stops the petrol to go in when car is switched in CNG mode
If Emulator is faulty it could cause mixing of both fuels and engine stalls
Emulator controlls the Fuel Injectors (aka Plungers). Even if one node of emulator is faulty or intermittent you will face extremely strange knocks and even backfires.
Advancer is installed to improve pick of vehicle esp when car is accelerating, If your car is problem in idling also then Advancer is not problematic. Your Car should run smoothly even if it fails but with low pick while accelerating.
If Incorrect Advancer is installed it could seriously damage the engine, cause frequent backfires, blow off air-cleaners etc, knock the engine, etc. Installation of it is not a layman's job. You must know how it works
The Advancer when installed adjusts the spark timings so that CNG may burn at proper time. If Advancer is misbehaving you are in thick soup.
Rest there is nothing complicated
EFI engine on CNG gives you no-fuss startup
Autoswitching is also a cool feature
Your battery and cranking system has no effect unlike non-efi cars