There is a good tool in autocad, artcam wich you cam youse in figma, this will make work easier.
First, you choose this instrument, second, set the corner radius, then tap on the corners on which you want to be rounded. it can be rounded or beveled corners.
when i have some interactions on some of artboards (not all), and when i choose artboard wich have not them, i cant see them in present mode. So, please, just look, how it works in Adobe XD(prototyping too), you choose artboard, tap play button, and it present what did you choose.
Tool scissors. Very useful to work with vectors. It remove section, part of vector, wich is restricted by two intersections/nodes