did you actually tag the static mesh? it’s not searching for the plain name of it. it’s a specific tag. that’s in the details section of the actor. alternatively you could add a static mesh component to the blueprint and load it directly. i’ve just done a quick level blueprint to test the whole mechanic. a dedicated “planet” blueprint and some logic would be appropriate. up to you to develop that. do your gamedev thing and integrate it into your logic. i did just prototype it.
and well… shadows are limited by the cascaded shadow map resolution. the further you are away from the camera the smaller the shadow resolution. that is to be expected. you gotta get the camera closer for better shadow quality or mess with the distribution bias or perhaps the csm resolution. raytraced shadows do work aswell, but you’d loose the distance field shadows and cannot set any distance to get the eclipse effect. if you don’t need that, it’s an alternative you have.