Time of day

Hello, Your Honor,
I wanted to ask whether you think there is any point in spending Shabbat during the time of Rabbeinu Tam’s Tzahak.
Rabbi Ovadia, zt”l, believes that since this is how the author of the Shulchan Aruch ruled, and many Rishonim also believe, it is appropriate for every heaven-fearing person to be strict about this, especially since we see that there is no complete darkness during the time of the exodus according to the Geonim, and this reinforces the opinion of Rabbi R. that there are two sunsets.
And it’s hard for me, because a baby born on Shabbat night during the time of the Exodus of the Ge’onim, all agree, including Rabbi Ovadia, that he be circumcised on Shabbat, even though there is doubt about the Torah prohibition according to the method of the Rabbis (in his opinion, the baby was born on Friday). And how do we treat something so severely that we treat it like a scoundrel in the prohibitions of the Torah, or alternatively, why don’t we reject circumcision because of this claim? Isn’t this overwhelming evidence that the method of the Rabbis has been completely rejected in its practice?
Likewise, Rabbi Ovadia zt”l claims that it should not be said that this opinion is only correct abroad, since the author lived in Israel, and hence it is proven that he ruled this way in Israel as well, and since he was a rabbi, it is appropriate to be as strict as he was.
And I have a hard time with that, so how do all the Ama Dara and the Tathagata practice today without following the ruling of the author’s Maran if he was the ruling of the generation in their time? I assume of course that this did not begin with the last generations after the author. (And the same problem, by the way, is difficult for me regarding the Tefillin of the Darat, and what did they practice until then? How were the parashiot of all the generations before them arranged? And so on.)
I would love to hear your opinion on the matter.