Frontend UI limitations

Hi, I am new to cuba working on an already deployed project, we need to redesign the UI and switch from generic UI to Frontend UI, so are there any limitations to it and if yes then what are they

CUBA itself is considered a legacy product. The same for its Frontend UI - it won’t receive much improvements or bug fixes, or library updates in the future as you might expect. So it isn’t a great idea to start new project using a Frontend UI.
If you really need to implement a data-intensive frontend UI for existing application, I would recommend you to start the project using React Admin or Refine frameworks, and implement a Data Provider (it’s a concept in both frameworks) that connects to the CUBA application via REST API in a generic way.

Hi, we are also expanding our project and planning to add new features to our application, so shall we stick to CUBA or first migrate our project to JMIX or other frameworks? What would you recommend?

To migrate from CUBA to Jmix, you will need to invest some time, depending on the size and complexity of the project.
So, if your project is in the low-cost maintenance stage, it can be kept on CUBA.
But if you plan to expand it and develop more features, then migrating to Jmix makes sense.