A similar thing is in use for mainframe applications to this very day to try to "modernize" them.

Basically fancy screen-scrapers that turn everything into forms and menus and fields, they do have their use. (In the industrial case, it's for things like text entry and mainframe applications to be made more "touchscreen friendly" for modern industrial devices and modernize them to the modern metal you have to use.)

I'm not sure how they're rendering in the browser. But if the TUI is rendered to DOM elements and not canvas/webgl, perhaps it could be useful to use a browser automation tool like Playwright to run test suites against the TUI. If your project involves CLIs and web apps interacting with one another, you could exercise them and assert their behavior within the same test framework.