The CC is an indicator, but is not definitive. The regulation is definitive. If they conflict, the CC is, by definition, wrong.
As has been said, limit raises in competition are not alertable in the ACBL.
Generally speaking, it's easier on the blood pressure *not* to assume that opponents are cheating.
If it becomes blatant, that's a different story, but I would tend to assume most players are honest until there is definite evidence otherwise. Aside from that, some people honestly think that alerts are for partner's benefit. They're wrong, but the answer to that is education (for which you should call the TD and let him do it, assuming there is one).
Alerting may slow down the game, but opponents are entitled to full disclosure, and alerts are part of that.