Thank you very much for sharing your experience.
I am still not a lawyer, but if Mom has already been declared non compos mentis, then 1: dozens and dozens of decisions as to her future have been removed from your control. 2: It becomes incumbent upon you to gain State approval for literally everything you or your sib does affecting her or on her behalf from here on out. Every vase, every fork, every piece of furniture disposed of has to be run past the admin who will be charging you for every phone call or document. 3: you and your sib now have to be very careful of elder abuse law in your state and you have furthermore have someone watching you and your sib who might well think they have something to prove. And who has a “free shot” at anything they might wish to come up with as they are automatically ratified by the state. 4: virtually all opportunities for estate planning are gone.
I hate to be the bearer of bad news but this is bad news. In CA, admittedly an expensive state, this all amounts to perhaps 1.5 years and about $40-$50K of extra costs that will come out of the estate before you see anything. I am not saying that you gaining whatever you think you should from her estate is any sort of priority for you. I am saying that any sort of dispute of size between you and your sib is $1000 an hour with 2 lawyers and the administrator and attys cheerfully billing for their time and getting paid first. Consider carefully, relative to the size of the estate whether any of it is worth it.
I spoke about how my personal situation was handled. But I also get involved in other situations, because my brother is frequently appointed attorney-in-fact to many estates that fall into dispute and I assist him on some cases. I have cleaned out hoarder houses. We have managed extensive remodels, removed kilotons of junk from derelict houses, extensively researched family trees where heirs have continued to live on houses where the original owners died in 1908 and the heirs married, divorced, had kids, died, kids died, heirs went to prison, died in prison, transferred fractional ownerships to others, sometimes defectively, house burned down, with child support and mechanics liens across multiple states. So I have lots of experience in this area. Most of it is pretty damn gritty.