What are the reasons for migrating an application to a newer technology [closed]

This type of question is offtopic for the site, but it follows view below.

As you yourself said, the biggest problem is not the technology (JSF) but rather how the components and classes of business were programmed. Whether you choose java, .net, php or any other language, if you are not aware of how to make the most of these technologies without giving up mvc / mvvm, you will continue to make low-maintenance software. You also need to have staff who are willing to do things with quality and within a proposed standard, how many of us have not seen some relaxed programmer putting that inside a controller?

It's important to know that when you quit JSF you lose some of the productivity that component development delivers, but you win on the other side by having an action-oriented backend that is easier for developers with less experience.

Angular with WebAPI would have a slightly different architecture than Asp.net MVC.

Nowadays, I can not see large systems being delivered with quality without the use of techniques like TDD & DDD.