Translate Strings in html tags for wordpress plugin

I have two files for my wordpress plugin.

class-a.php

/* 
Text Domain: class-a
Domain Path: /languages/
*/
class-a {
    include( plugin_dir_path( __FILE__ ) . 'class-b.php' );
}

class-b.php

class-b {

 function some_function{
   <div><h2>Some text</h2></div>
 }

}

I am trying to add translations to my plugin, and I am able to translate all the string in the class-a.php but I am facing issues translating string in class-b.php. I am assuming since class-b is included while class-a is loaded, the same text domain applies for class b as well.

My question

1. Is my assumption right that the same text domain applies for class-b as well or I should add separate text domain for class-b
2. What is right way to translate the html string.