If all simulators are unreliable, and X is a simulator, then X is unreliable. Once you hear BBS declare his opinion that covers all of them, following back up to ask him "yes, but what about this particular one?" is unlikely to get you a different answer.
I’m referring to the simulator on MyFico website. Is it an accurate simulator and can the revolving balance on the simulator update each month?
No it's not an accurate simulator.
Yes the balances it's referring to are updated.
The reason all simulators are notoriously incapable is that they only take into consideration a handful of factors (the 10 questions or whatever they ask at the start) when there are far many more factors that go into a credit report and an infinite amount of factors at play when considering them all relative to one another.
The only way you'd get something accurate is if you found something that took into consideration your entire credit report... and that's the purpose of a FICO algorithm that yields a score.