properly format strings per ruleset

osu.Game.Rulesets.Catch/Objects/CatchHitObject.cs

@@ -120,5 +120,7 @@ namespace osu.Game.Rulesets.Catch.Objects
         }
 
         protected override HitWindows CreateHitWindows() => HitWindows.Empty;
+
+        public override string ToEditorString() => (IndexInCurrentCombo + 1).ToString();
     }
 }

osu.Game.Rulesets.Mania/Objects/ManiaHitObject.cs

@@ -22,6 +22,8 @@ namespace osu.Game.Rulesets.Mania.Objects
 
         protected override HitWindows CreateHitWindows() => new ManiaHitWindows();
 
+        public override string ToEditorString() => $"{StartTime}|{Column}";
+
         #region LegacyBeatmapEncoder
 
         float IHasXPosition.X => Column;

osu.Game.Rulesets.Osu/Objects/OsuHitObject.cs

@@ -130,5 +130,7 @@ namespace osu.Game.Rulesets.Osu.Objects
         }
 
         protected override HitWindows CreateHitWindows() => new OsuHitWindows();
+
+        public override string ToEditorString() => (IndexInCurrentCombo + 1).ToString();
     }
 }

osu.Game/Rulesets/Objects/HitObject.cs

@@ -168,6 +168,8 @@ namespace osu.Game.Rulesets.Objects
         /// </summary>
         [NotNull]
         protected virtual HitWindows CreateHitWindows() => new HitWindows();
+
+        public virtual string ToEditorString() => string.Empty;
     }
 
     public static class HitObjectExtensions

osu.Game/Screens/Edit/Editor.cs

@@ -558,7 +558,7 @@ namespace osu.Game.Screens.Edit
             {
                 var orderedHitObjects = editorBeatmap.SelectedHitObjects.OrderBy(h => h.StartTime);
                 builder.Append(orderedHitObjects.FirstOrDefault().StartTime.ToEditorFormattedString());
-                builder.Append($" ({string.Join(',', orderedHitObjects.Cast<IHasComboInformation>().Select(h => h.IndexInCurrentCombo + 1))})");
+                builder.Append($" ({string.Join(',', orderedHitObjects.Select(h => h.ToEditorString()))})");
 
                 clipboard.Value = new ClipboardContent(editorBeatmap).Serialize();
             }