Custom, interpretation of Chazal

Peace and blessings
I wanted to ask the rabbi to show the root of the discussion on the issue of custom in one point that leads to two heads. 1- The source/reasoning that the custom is binding even in a place where it is known that the truth is not according to his words (for example, the Maimonides who elevates the first priest to the Torah despite the fact that there is a scholar of his, even though in the rebuttal he attacked this opinion. And he justified the ruling on the halachic law that they already practiced this) 2- It makes a lot of sense to me that it is absolutely impossible today to renew customs – for example, it is clearly unlikely that lighting bonfires on Lag BaOmer in another 100 years will be able to become a custom that is binding on every community and synagogue…. And from a simple explanation it seems that when the root of the custom is known, in halachic and historical literature, then it is a barren custom. So, can it be argued that there is a certain point – for example, the development of printing or the spread of printing – that no new custom should be accepted. (And if we do point to such a point, it is a bit difficult to understand why Maimonides ruled to appoint a priest, even though it is clear that the root of the custom is the error in understanding the words of the sages in the Talmud. And the Talmud was widespread enough… And I do not believe that Lag BaOmer bonfires would indeed be a custom if people did not study history… In other words, it is unlikely that a custom could be accepted if knowledge about it is not widespread among people, even though it is available to anyone who seeks knowledge.)
I apologize in advance for the above question. I assume that the Rabbi has written extensively on the site (and indeed I remember reading things about this matter on the site in the past, but I have not found a place that puts his finger on this point).
Another enlightenment.
I recently read an old article (2011, to the best of my memory) in which a rabbi wrote about the abrogation of the laws of the Sages in places where the reason is invalid or where the explanation seems to indicate that they were mistaken in their interpretation. I wanted to point out the words of the Yerushalmi in the instructions, chapter 1, "As a religious person, if they tell you on the right that it is left and on the left that it is right, you will listen to them and go right and left, even if they tell you on the right that it is right and on the left that it is left" (and one should also add the words of the rabbi in Yevamot 27:1, which are mistaken in the reality of the 38th instruction).
Another important source is the Maimonides' reply to the question of marrying a "fatal" woman – "I am astonished, I am greatly astonished, that dear scholars who are always busy with the Torah would be satisfied with the degrees of prohibitions up to this point and would not distinguish between what is forbidden from the Torah and what is only obscene and there is no prohibition in it. And what is even more astonishing in your question is the comparison of the laws of souls, etc., which are feared through divination and witchcraft and imaginations and images, etc., except that our opinion is that it is considered obscene to marry other people, but there is no prohibition in this at all." And there is no difference between a man who marries a woman who is being held or who eats from a gluttonous woman, and so on. And in practice, in all Andalusian countries, (if) a woman's husband dies, she will always have several husbands. She will not be prevented from marrying, especially when she is in her prime because of the loss that must be felt in this. And we have already found that the sages of the halmud permitted transgression of the prohibitions of pleasure and released her until there remained no obstacle for the intruders, and how could we, the daughters of Israel, risk going out into a bad culture, etc. And so did the court of our Rabbi Yitzchak, the author of the law, and so did the court of our Rabbi Yosef Halevi, his disciple, the late Rabbi, and so did everyone who came after them, and so did we in the land of Egypt and so did we since we came to it.
(It should be noted that these words of the Rambam mean that the Sha'sh means to say that from the side of custom they accepted in a comprehensive manner all the words of the Talmud. And this also opens the door to the question mentioned in the laws of custom.)
(And just a small note. The Rabbi noted the words of the Toss in Yevamot 5:1 regarding the matter of the witness. I believe that the explanation in the Toss leans towards the words of the Ritva, where regarding the witness's loyalty, I rely on the word of the Da'al (and the Ritva added the word "she" – and the Rabbis, as the Rabbis wrote at the end of the divorce laws in the word of the Da'al, "she is faithful to the da'ariyta" and omitted the word "she"), and the scripture conveyed to the sages, etc., and the simple explanation is that what is believed in a witness is only because he truly saw/thought as he testifies to us. But this is not enough for me to know the Bible. And this is the scripture conveying to the sages whether to trust and accept the witness's words for themselves or not (and as the well-known explanation of the Chazo"a on the word of the Ritva above).
Thank you very much. In general, about the writing in quality and quantity. And in particular, about the response to every question and this one in general, "the individual."