Manually add game speeds to the linter.

OpenRA.Game/GameSpeed.cs

@@ -16,6 +16,7 @@ namespace OpenRA
 {
 	public class GameSpeed
 	{
+		[TranslationReference]
 		[FieldLoader.Require]
 		public readonly string Name;
 

OpenRA.Mods.Common/Lint/CheckTranslationReference.cs

@@ -58,6 +58,15 @@ namespace OpenRA.Mods.Common.Lint
 				}
 			}
 
+			var gameSpeeds = modData.Manifest.Get<GameSpeeds>();
+			foreach (var speed in gameSpeeds.Speeds.Values)
+			{
+				if (!translation.HasMessage(speed.Name))
+					emitError($"{speed.Name} not present in {language} translation.");
+
+				referencedKeys.Add(speed.Name);
+			}
+
 			foreach (var modType in modData.ObjectCreator.GetTypes())
 			{
 				foreach (var fieldInfo in modType.GetFields(Binding).Where(m => m.HasAttribute<TranslationReferenceAttribute>()))