A simple editor extension to enable unityevent reordering (draggable) feature. I don't know why it is not a default setting.

Tested with Unity 2020年3月5日f1

Just put the code inside an Editor folder

using UnityEditor;
using UnityEditorInternal;
using UnityEngine.Events;
[CustomPropertyDrawer(typeof(UnityEventBase), true)]
public class ReorderingUnityEventDrawer : UnityEventDrawer
{
 protected override void SetupReorderableList(ReorderableList list)
 {
 base.SetupReorderableList(list);
 list.draggable = true;
 }
}

Don't rely on the execution order of the events, use it only for "organization" purposes.
In your project, the execution order will probably work, but when you or a teammate import/reimport your project, the results could be different.
The list will be orderer but the execution could not.

I'll not explain here but you can search for UnityEvents C# delegates order and get good explanations.