You couldn't find a gui designer for intellij, so you consider rewriting the whole application? in C++?!
Would seem easier to learn that ui framework.
For UI maybe look into javafx as an alternative. I haven't used it, so can't tell how the design process goes. But it seems to be the only current ui framework for Java.
That was a decade or two ago. Now you need a react SPA webapp using angular and Rust and utilize the bandwidth of the Cloud with machine learning. To find the IP.