JSFiddle - React, Tailwind, and code Playground

HTML

<h3 title="Оригинальный текст">Текст</h3>

CSS

h3 {
  text-decoration: underline;
}
[title]::after {
  content: "[en]";
  font-size: 0.5em;
  vertical-align: top;
  text-decoration: none;
}