Keyframe reduction in Rotation is not correct.

I am working on a script that does keyframe reduction for animations, but when I do the keyframe reduction with the following code, only the Rotation is not done correctly. To be exact, x is working, but some of the values for y and z seem to have changed. How can I modify the source code to do the key reduction for Rotation?

 using System.IO;
 using System.Linq;
 using UnityEngine;
 using UnityEditor;
 using System.Collections.Generic;
 using System;
 
 public class KeyReductionTest : AssetPostprocessor
 {
     [MenuItem("Assets/Key Reduction Test")]
     static void KeyReduction()
     {
         Debug.Log("Key Reduction Test...");
         foreach (UnityEngine.Object obj in Selection.GetFiltered(typeof(AnimationClip), SelectionMode.Editable))
         {
             string path = AssetDatabase.GetAssetPath(obj);
             AnimationClip anim_clip = (AnimationClip)AssetDatabase.LoadAssetAtPath(path, typeof(AnimationClip));
 
             foreach (var binding in AnimationUtility.GetCurveBindings(anim_clip).ToArray())
             {
                 AnimationCurve curve = AnimationUtility.GetEditorCurve(anim_clip, binding);
                 AnimationCurveKeyReduction(curve, binding.propertyName, 0.001f);
                 AnimationUtility.SetEditorCurve(anim_clip, binding, curve);
             }
             string anim_clip_name = Path.GetDirectoryName(path) + "/" + Path.GetFileNameWithoutExtension(path);
             WriteAnimationCurve(anim_clip, anim_clip_name);
         }
     }
 
     static private void WriteAnimationCurve(AnimationClip anim_clip, string anim_clip_name)
     {
         string tmp_name = anim_clip_name + "_tmp.anim";
         var copyClip = UnityEngine.Object.Instantiate(anim_clip);
         AssetDatabase.CreateAsset(copyClip, tmp_name);
         FileUtil.ReplaceFile(tmp_name, anim_clip_name + ".anim");
         AssetDatabase.DeleteAsset(tmp_name);
         AssetDatabase.Refresh();
     }
 
     static private float GetValueFromTime(Keyframe key1, Keyframe key2, float time)
     {
         float t;
         float a, b, c;
         float kd, vd;
 
         if (key1.outTangent == Mathf.Infinity) return key1.value;
 
         kd = key2.time - key1.time;
         vd = key2.value - key1.value;
         t = (time - key1.time) / kd;
 
         a = -2 * vd + kd * (key1.outTangent + key2.inTangent);
         b = 3 * vd - kd * (2 * key1.outTangent + key2.inTangent);
         c = kd * key1.outTangent;
 
         return key1.value + t * (t * (a * t + b) + c);
     }
 
     static private bool IsInterpolationValue(Keyframe key1, Keyframe key2, Keyframe comp, float eps)
     {
         var val1 = GetValueFromTime(key1, key2, comp.time);
 
         if (eps < System.Math.Abs(comp.value - val1)) return false;
 
         var time = key1.time + (comp.time - key1.time) * 0.5f;
         val1 = GetValueFromTime(key1, comp, time);
         var val2 = GetValueFromTime(key1, key2, time);
 
         return (System.Math.Abs(val2 - val1) <= eps) ? true : false;
     }
 
     static public IEnumerable<int> GetDeleteKeyIndex(Keyframe[] keys, float eps)
     {
         for (int s_idx = 0, i = 1; i < keys.Length - 1; i++)
         {
             if (IsInterpolationValue(keys[s_idx], keys[i + 1], keys[i], eps))
             {
                 yield return i;
             }
             else
             {
                 s_idx = i;
             }
         }
     }
 
     static public void AnimationCurveKeyReduction(AnimationCurve in_curve, string propertyName, float eps = 0.0001f)
     {
         if (in_curve.keys.Length <= 2) return;
         var del_indexes = GetDeleteKeyIndex(in_curve.keys, eps).ToArray();
         foreach (var del_idx in del_indexes.Reverse()) in_curve.RemoveKey(del_idx);
     }
 }

before key reduction: after key reduction: