I don't think it's possible to talk about an average in a polarized society like Chile was. And although I also hate to use the ideological model of cold war mechanically, it explains more or less that polarization.

So we have two averages of people. In the '73 coup we would have those who judged the action as saving the country from the dictatorship of the proletariat. And on the other hand a tragedy of historical proportions, the leftist people who supported the government had lost the historical opportunity to achieve socialism, a unique moment in the history of this country.

What happened in summary in the government of the UP is that the people who supported Allende wanted more radical changes, but the president had to do it in a legal way, therefore the speed of those changes was impossible and interpreted by the people as the bourgeois side of Allende. For example the government program voted in the ballot box contained the expropriation of 120 private companies, about 500 were expropriated by the workers without the legal consent it required. So for the right Allende was a fierce Marxist, and for the hard left he was an opportunistic bourgeois, because in the most tense moments Allende did not let the political parties take the weapons they had in store for the moment of class confrontation. They recommended that Allende remain president and lead the civil war along with the loyal armed forces but he preferred to die in La Moneda rather than drag the country into such a fate. For such a scenario to occur there were protests in favor of the government and against the government of the left itself, as well as protests against it from the right and center-right.

The average right-wing person is easy to explain since ideologically they had a common enemy despite internal differences. The left, on the other hand, while agreeing that the enemy was imperialism and the national bourgeoisie, was quite divided against Allende. Some tried to call him a coward for not arming the people, some of whom later realized that Allende's altruism in the face of the sacrifice of one man was in contrast to that of many. If there was a change in the people of the hard left, it was from the disappointment of not achieving the revolution to understanding the coming massacre (not of the victorious revolution but of the civil war process). In that process of disenchantment some abandoned Marxism-Leninism, others reaffirmed it by seeing the counter-revolutionary forces save their owners (the national bourgeoisie with financial and logistical support from the United States).

I don't know if there are any dailies or diaries. But there are tons of memories of the time, but probably most of them have not been translated into English. Some of them surely are. I could give you the name of the works in Spanish if you are interested.