While I appreciate the creativity around using a game engine for non gaming applications, this does not seem like a particularly good fit.
If most of your problem is 2d window/text stuff, the web browser is probably the best foundation to work with. UI and hud functionality in COTS game engines is light years behind what chromium and friends can do today.
If most of your problem is 2d window/text stuff, the web browser is probably the best foundation to work with. UI and hud functionality in COTS game engines is light years behind what chromium and friends can do today.