Been looking for the same kind of solution myself.
It appears that the material elements of a static or skeletal mesh are numeric indexes that are assigned to converted surfaces/face groups on a first come - first serve basis during content import.
Hence, the only guarantee that your mesh’s material “element 3” will be their torso for example, is if the order of surface/face groups remains the same when imported from whatever 3D modeling software you happen to be using.
If you make significant changes to your surface/face group list, in Blender for example, if the order of surface/face groups changes, then they’ll receive different material element indexes from your previous version of the same imported asset.
Ideally, we need a utility that adds a context menu item when we right-click a static or skeletal mesh, that pops up a spreadsheet in the unreal engine interface with columns for “material element #” and “selected material”, that when we click on a row as you’ve all stated in this post, the correct group of faces from the mesh are highlighted, with the added feature of saving this spreadsheet to comma separated ascii (.csv) or a plain text file, unless I’ve missed a feature in UE5 that I don’t know about.