I missed that feature - to set separate corner radius. But please, add proper export to CSS when corners are different. There are a lot of features to borrow from Axure I'd like to see in Figma.
A question to community, if you're the one who jumped from Sketch to Figma recently, so what's your reason?
My reason: as the independent UI/UX problem solver I'd like Figma's code export feature. It helps me to establish the connection with developers team of my every client.