I guess it's saying some body parts cannot be hit due to their coverages.

BodyDef Hound has BodyPartRecord of MechanicalThorax whose children have more or equal total coverage than 1. This means parent can't be hit independently at all.
Verse.Log:Warning(String)
Verse.BodyDef:CacheDataRecursive(BodyPartRecord)
Verse.BodyDef:ResolveReferences()
Verse.DefDatabase`1:ResolveAllReferences()
System.Reflection.MonoMethod:InternalInvoke(Object, Object[], Exception&)
System.Reflection.MonoMethod:Invoke(Object, BindingFlags, Binder, Object[], CultureInfo)
System.Reflection.MethodBase:Invoke(Object, Object[])
Verse.GenGeneric:InvokeStaticMethodOnGenericType(Type, Type, String)
Verse.PlayDataLoader:DoPlayLoad()
Verse.PlayDataLoader:LoadAllPlayData(Boolean)
Verse.Root:<Start>m__84E()
Verse.LongEventHandler:RunEventFromAnotherThread(Action)
Verse.LongEventHandler:<UpdateCurrentAsynchronousEvent>m__84C()

BodyDef Kraken has BodyPartRecord of MechanicalThorax whose children have more or equal total coverage than 1. This means parent can't be hit independently at all.
Verse.Log:Warning(String)
Verse.BodyDef:CacheDataRecursive(BodyPartRecord)
Verse.BodyDef:ResolveReferences()
Verse.DefDatabase`1:ResolveAllReferences()
System.Reflection.MonoMethod:InternalInvoke(Object, Object[], Exception&)
System.Reflection.MonoMethod:Invoke(Object, BindingFlags, Binder, Object[], CultureInfo)
System.Reflection.MethodBase:Invoke(Object, Object[])
Verse.GenGeneric:InvokeStaticMethodOnGenericType(Type, Type, String)
Verse.PlayDataLoader:DoPlayLoad()
Verse.PlayDataLoader:LoadAllPlayData(Boolean)
Verse.Root:<Start>m__84E()
Verse.LongEventHandler:RunEventFromAnotherThread(Action)
Verse.LongEventHandler:<UpdateCurrentAsynchronousEvent>m__84C()