If that becomes an issue, getting an honest-to-goodness admin involved should straighten it out rather quickly, as the servers otter remember what alterations were done and when.
More on-topic, the payscale for measurable and tracked skills is only as good as your (and your employees') honesty. Back at Big Tier 1 Auto, Inc. (multi-billion NA branch of a privately owned Japanese company) they had one of those and it didn't do me a bit of good. I wasted half a day scoring myself as honestly as I could in 40-50 skills, and once I realized that I rated solidly as an ENG III and looking at Sr ENG sooner rather than later, I thought I could bully myself into a raise, as I was ENG II at the time. Turns out I didn't have enough "points" on their other (HR-based) pay-scale tier list, I had some for a BS in Engineering, and some more for my years of experience, but wasn't enough for the next pay grade. The end result is that management blew me off whenever I brought up the skill chart, and ended up sweeping the whole thing under the rug as best they could for the whole group, presumably because it was causing more headaches than it solved. Never challenged me on any of the skill rankings, just that the skill chart alone wasn't enough to get me the next level.
Don't be like that if you're going to bring it up.