We need better and more clear way to clean up and remove unneeded items, or to more easily coordinate clean-ups, including object styles. Preferably, Revit would overwrite the family linestyle names as well but maybe it's too much to overwrite a file that is potentially not even open.
Or if an object style's definition (properties, not name string) matches one in the project, rename to apply the project's objectstyle name to the family's object style.
Or there could be a pop up when deleting any object styles that are in use: "The following object styles are in use and will be changed to: ____ ", <user selected drop down>
Example: Deleted object style line under Doors called 'Dr-Elev', and drop down appears- User can switch to: <select 'Opening Elevation'>
Or force naming conventions within the Revit families, limiting the number of custom line types in families that are not generic models