Custom text in theme through functions.php

Now, I know the standard of fixing custom text is usually done through editing the php of a child theme, but I want to become more proficient in using functions, which seems like a similar robust solution, is it not? I saw it recommended a few places at least.

I am using the Avada theme and I want to change a few bits here and there to my native language (a few bits missed by the current .po / .mo files).

I found this piece of code that I do sort of understand.

    function tribe_custom_theme_text ( $translation, $text, $domain ) {
    	$custom_text = array(
    		'something %s' => 'something %s',
    	);
     
        	if( (strpos($domain, 'tribe-') === 0 || strpos($domain, 'the-events-') === 0 || strpos($domain, 'event-') === 0) && array_key_exists($translation, $custom_text) ) {
    		$translation = $custom_text[$translation];
    	}
        return $translation;
    }
 add_filter('gettext', 'tribe_custom_theme_text', 20, 3);

But I have a few questions!

Firstly, is this the proper way of doing it (if not how)?

Secondly, if so; how do I go about identifying the text domains?