Ah, thanks for clearing that up.
I don't think it's "promote 1-6 from inside, then one outside, then 6 more inside, then one outside" necessarily. The intent of the language was the ratio, so if they are going to promote 14 people to driving, 12 would have to come from p/t and 2 from outside or management. If they are going to promote 5 people to driving and can't satisfy the ratio but want to use an outside hire they would need to commit to promote another person from inside before the end of the year.
I'm assuming your scenario is that they have promoted 12 to driving and now they are on the 13th? It seems they would still be satisfying the ratio if they did an outside hire, but definitely file and get with your BA and see what the practice has been. It may very well be that the 7th hire is outside and if it's skipped they have to wait til they hire 6 more. All it will waste is 2 minutes of your time and a sheet of paper to find out the answer. If you are right they could train you but adjust your seniority date to be before the 'illegal' hire.