What are some drawbacks of this political system based on noocracy and demarchy?

Evidently, representative democracies of today are far from perfect. The main issues I see are:-

1. The majority of voters being poor, undereducated, lacking interest and education to choose the most appropriate
   candidates, even for their own interests. This leads them to vote based on instinct or habit and not analysis.
2. Lack of choice in candidates, inefficacy of "against all" voting and great difficulty in running for office yourself which
   forces a voter to vote for "the better of two bad choices".
3. The great potency of money in brainwashing the general public( by spreading misinformation, buying media houses
   etc. )which is easy to access by a politician who works in the interests of the rich after being elected.
4. The agreement of several parts of government (like different houses) required for drastic change, which is often rare. Although useful to prevent one person doing too much damage, it also slows down the rate at which a good leader can bring about positive change. Gun control is a prime example of this.
5. The division of powers not being effective enough with the judiciary not being as independent or powerful as the executive/legislature. For example, heads of states commonly appoint judges matching their ideology.
6. General politics(not just elections) usually focussed around very few people, such as the president and his main election rival which leads to extremely high levels of fame and publicity to them. This ultimately reduces opposition by common people because they tend to assume that the "millions of people" are with that person. This effect helps a leader become autocratic.
7. Weak constitutions which enable the rise of autocratic leaders.

I have been reading about various forms of government, and I feel that a mix of demarchy and noocracy would solve most of the above issues. The key principles would be:-

1. An initial jury which will be composed of humans of very high moral standard and intelligence. Some people may argue that quarrels can break out even amongst them, but in my personal experience, the kinder and more intelligent a person gets, the better he /she is able to able to control his/her ego and think critically together for making the world a better place. Often, it is not hard for a group of good people to get along well in the long term and more harm is done when power is concentrated in the hands of a single, bad person. This jury will be given very high levels of power in certain areas but very little in others(see point 5). The jury will operate for a moderate period of time(e.g.10 years). A spokesperson will be chosen(not part of the jury and without any power), whose sole job would be to present the decisions of the jury to the public in an appealing manner. The spokesperson will change much more frequently, for example every 2 years. Also, the jury will not be given exacerbated levels of fame and that will remain with the spokesperson.
2. The selection of future juries will be done in two parts. The first being a test of a candidate's knowledge on basic requirements to become a juror. The test will not be competitive and a book will be published which any literate person can read and prepare for. From the candidates who qualify, a small and reasonable number will be chosen by lottery who will then proceed to the next stage of the selection process.
   The second part will be an internship period where the current jurors will be able to work with the candidates and get to know their competence in administration as well as their morality. Each juror will then select a suitable candidate to replace him/her. This is much better than a short interview where it is difficult to assess someone's personality.
3. A constitution where it is impossible to make changes to laws where it is extremely probable that no future changes will be required. This will include obvious laws like gender and racial equality but also areas pertaining to the structure of the government. Examples could be not allowing a juror to become a spokesperson either before, during or after he/she is part of the jury, term lengths of the juror etc. However, in other areas like choosing high-ranking officials in the judiciary, executive, army etc. and making laws in non-restricted areas, the jury will be given very high levels of power, equivalent to a dictator.

Ignoring the feasibility of bringing about this system in the real world, what are possible downsides of this system and is it possible to solve them by making certain modifications to this model?

P.S: I am new to this site(and stack exchange as a whole) and politics is an interest of mine rather my mainstream work (which is science). Thus, it is difficult for me to ask this question without it seeming slightly broad. However, I feel that the slight broadness of this question doesn't mean that it gives leeway to opinionated answers because the ideas involved here have been used in some modified form either in the past or present. History and knowledge of a spectrum of political ideas can certainly be used to give some basis.