Your A-J example is a perfectly acceptable way of fairly picking a value. Assuming each of the 10 values have an equal chance of being picked, then they each have a 90% chance to fail their roll. The odds are strongly against any of them from being picked, that's what makes it fair. Provided the order of the values always remains the same, the "magic number" that needs to be rolled for a winner to occur is the same for each value, and finally and most importantly failed rolls are not removed from the pool then this system will work fine. In a way actually, the last value has a bit of an advantage in situations where a winner must be picked, because if nothing was picked above it, it has to be picked even if it was going to fail its roll. After all, odds are we'll get to that last number every 10th try
Now, this system works best if each value has an equal chance of being picked. If not, then the values must be listed in order from lowest probability to highest. If EQEmu does not do that, then we have an issue.