This has to benefit of being able to use the exact same database and update the schema over time with your API, completely independent of the front end.
You don't specify whether your app is currently desktop or web based. Hitting the enter key has been the standard way to submit HTML forms since the very early days of the internet. Why would you need a special library to support that?
Since you're asking about C/Qt I'm assuming the current app is desktop based? Having just completed a client project migrating a large desktop-based application to the web (C# API, Angular front-end), work flows are going to have to change to at least some degree. It is very rare to be able to cleanly, easily port 100% of the desktop experience to the web. If that's a deal breaker, make sure it's not worth it to stick with the desktop. You can still separate your concerns and provide a modern experience.