When you use openkore on official, how do you get banned for it?
You send the bot to hunt monsters.
When you have the recources and time to create an FCP bot, however, it is a different matter. Bring yourself to a private location, set a less obvious cool down and wait time on FCP, and it will fcp you conveniently. You won't get banned.
If you have the recources and time to make and support the buff/fcp bots, there will always be a way, it is just the main requirement. It's a high rate, we get 255 in a day, find 600 glistening coats in an hour, and we're not out there botting monsters, we're just making a creator stand in town and FCP us. If you want to do it on official, just make it look like you're dual clienting, if they had a way to detect openkore, you wouldn't see so many bots on iRO.
If for some idiotic reason, dual clienting is not allowed, there is still no way to prove whether or not you are dual clienting, or your friend surfing the internet on his other comp is FCPing you on que.