Simple Unity script to capture an object position delta movement so you can easily apply it by exiting Timeline preview mode

MoveAnimatedCharacterMenuItem.cs

using System.Linq;
using UnityEditor;
using UnityEditor.Timeline;
using UnityEditor.Timeline.Actions;
using UnityEngine;
using UnityEngine.Timeline;


// Adding a new menu item to the move/rotate etc commands would be cooler!
// https://github.com/Unity-Technologies/UnityCsReference/blob/master/Editor/Mono/GUI/Tools/BuiltinTools.cs
// Also https://github.com/HiddenMonk/Unity3DRuntimeTransformGizmo looked interesting (a move gizmo)


// See https://docs.unity3d.com/ScriptReference/MenuItem.html

#if UNITY_EDITOR

namespace OrdinaryCartoonMaker
{
    public static class MoveAnimatedCharacterState
    {
        public static AnimationTrack track;
        public static bool markedPosition1Set = false;
        public static Vector3 markedPosition1;
        public static bool markedPosition2Set = false;
        public static Vector3 markedPosition2;
    }

    [MenuEntry("Mark Object Start Position", MenuPriority.CustomTimelineActionSection.start)]
    public class MarkStartAnimatedCharacterMenuItem : TimelineAction
    {
        public override ActionValidity Validate(ActionContext context)
        {
            if (!context.tracks.Any())
            {
                return ActionValidity.NotApplicable;
            }

            var track = context.tracks.First() as AnimationTrack;
            if (track != null && context.director != null)
            {
                // TODO: Really should be cleared when selection changes to a different track.
                if (track != MoveAnimatedCharacterState.track)
                {
                    MoveAnimatedCharacterState.track = null;
                    MoveAnimatedCharacterState.markedPosition1Set = false;
                    MoveAnimatedCharacterState.markedPosition2Set = false;
                }

                var binding = context.director.GetGenericBinding(track);
                if (binding != null)
                {
                    return ActionValidity.Valid;
                }
            }

            return ActionValidity.Invalid;
        }

        public override bool Execute(ActionContext context)
        {
            var track = context.tracks.First() as AnimationTrack;
            var binding = context.director.GetGenericBinding(track) as Animator;
            MoveAnimatedCharacterState.markedPosition1 = binding.transform.localPosition;
            MoveAnimatedCharacterState.markedPosition1Set = true;
            MoveAnimatedCharacterState.track = track;
            Debug.Log("MARKED START POSITION");
            Debug.Log(MoveAnimatedCharacterState.markedPosition1);
            return true;
        }

    }

    [MenuEntry("Mark Object End Position", MenuPriority.CustomTimelineActionSection.start)]
    public class MarkEndAnimatedCharacterMenuItem : TimelineAction
    {
        public override ActionValidity Validate(ActionContext context)
        {
            if (!context.tracks.Any() || !MoveAnimatedCharacterState.markedPosition1Set)
            {
                return ActionValidity.NotApplicable;
            }

            var track = context.tracks.First() as AnimationTrack;
            if (track != null && context.director != null)
            {
                // TODO: Really should be cleared when selection changes to a different track.
                if (track != MoveAnimatedCharacterState.track)
                {
                    MoveAnimatedCharacterState.track = null;
                    MoveAnimatedCharacterState.markedPosition1Set = false;
                    MoveAnimatedCharacterState.markedPosition2Set = false;
                }

                var binding = context.director.GetGenericBinding(track);
                if (binding != null)
                {
                    return ActionValidity.Valid;
                }
            }

            return ActionValidity.Invalid;
        }

        public override bool Execute(ActionContext context)
        {
            var track = context.tracks.First() as AnimationTrack;
            var binding = context.director.GetGenericBinding(track) as Animator;
            MoveAnimatedCharacterState.markedPosition2 = binding.transform.localPosition;
            MoveAnimatedCharacterState.markedPosition2Set = true;
            Debug.Log("MARKED END POSITION");
            Debug.Log(MoveAnimatedCharacterState.markedPosition2);
            return true;
        }

    }

    [MenuEntry("Move Object Position", MenuPriority.CustomTimelineActionSection.start)]
    public class MoveAnimatedCharacterMenuItem : TimelineAction
    {
        public override ActionValidity Validate(ActionContext context)
        {
            if (!context.tracks.Any() || !MoveAnimatedCharacterState.markedPosition1Set || !MoveAnimatedCharacterState.markedPosition2Set)
            {
                return ActionValidity.NotApplicable;
            }

            var track = context.tracks.First() as AnimationTrack;
            if (track != null && context.director != null)
            {
                var binding = context.director.GetGenericBinding(track);
                if (binding != null)
                {
                    return ActionValidity.Valid;
                }
            }

            return ActionValidity.Invalid;
        }

        public override bool Execute(ActionContext context)
        {
            var track = context.tracks.First() as AnimationTrack;
            var binding = context.director.GetGenericBinding(track) as Animator;
            var deltaMovement = MoveAnimatedCharacterState.markedPosition2 - MoveAnimatedCharacterState.markedPosition1;

            Undo.RegisterCompleteObjectUndo(binding.gameObject, "Move animated object position");

            binding.transform.localPosition += deltaMovement;

            Debug.Log("MOVED OBJECT");
            Debug.Log(deltaMovement);

            return true;
        }
    }
}

#endif