The first sentence means “then you could only hear complete silence“. One of the ways to express utter silence is to say that “un silence se produisit“, litteraly “a silence produced itself“. It expresses the fact that the silence is so intense it almost happened by itself and it sort of have its own existence that crushes the audience.

The second sentence reads “one happy thing is worth just as much as another“, which implies happiness has multiple forms and there can be no appropriate comparison between things that can make you happy. For all I know it is a common French saying.

Ce qui peut être difficile à comprendre dans cette phrase est l’emploi du pronom personnel en.

La phrase de départ est :

Un bonheur vaut un autre bonheur.

Pour éviter la répétition du mot bonheur on le remplace par le pronom personnel en et le pronom personnel doit être placé avant le verbe.

Le sens de vaut ne nécessite pas d’explication, car on peut retrouver facilement son infinitif et de là remonter jusqu’à son sens, voir à sa traduction.

In this sentence the difficulty lies in the use of en as a personal pronoun.
En replaces the second occurrence of the word bonheur in the sentence :

Un bonheur vaut un autre bonheur.

For more about the use of en please see here. You must know it is placed before the verb.

You can easily find the meaning of vaut by finding first its infinitive and then its meaning and even its translation into English.