No, haven't been banned for coin rush hack. Probably because it doesn't trigger the soft limits of the game and it's more believable to the auditing system than just straight editing the amount of coins you have (since you'd still be technically "earning" the coins), but you can't even edit the amount of coins you have straight up any more, so it's pretty much the most efficient option. It's also only a small incremental increase of coins, as opposed to a much higher number like 100k coins, so that may be another reason for not triggering ban. Still can't say that the coin rush method is worth it for the amount of effort you have to put in The yield is relatively small and quite underwhelming. If you want to hack though, doing it during races is the best time to do it with the least chance of ban.
[added 3 minutes later]
The time jump function is accessible from the main menu of Game Guardian. Find it, turn it on, and just enter the amount of time you would like to jump ahead. I use a time of about 5 minutes personally. Ends the races instantly when pressed. So just get into first place, press the time jump button, win the race, and repeat.