Once the have the data loaded we pass it into this function which identifies if there is an error.

IsEverythingFine.cs

public static bool IsEverythingFine(List<SubPicture> subPictures)
        {
            const int tolerance = 100;

            var labels = subPictures.Where(sp => sp.Label.Contains("label")).ToList();

            var maxItemY = subPictures.Except(labels).Min(i => i.TopLeft.Y);
            foreach (var label in labels.ToArray())
            {
                if (label.TopLeft.Y < maxItemY)
                {
                    labels.Remove(label);
                }
            }

            var boundries = new List<int>();
            var boundriesDict = new Dictionary<int, List<SubPicture>>();
            foreach (var label in labels)
            {
                var labelY = label.TopLeft.Y;
                if (!boundries.Any())
                {
                    boundries.Add(labelY);
                    boundriesDict[labelY] = new List<SubPicture>() { label };
                }

                var found = false;
                foreach (var boundry in boundries)
                {
                    //if slightly upper
                    if (labelY <= boundry && labelY + tolerance >= boundry)
                    {
                        //we are in the clear
                        boundriesDict[boundry].Add(label);
                        found = true;
                        break;
                    }
                    //if slightly lower
                    if (labelY >= boundry && labelY - tolerance <= boundry)
                    {
                        //we are in the clear
                        boundriesDict[boundry].Add(label);
                        found = true;
                        break;
                    }
                }

                if (!found)
                {
                    //not anywhere near
                    boundries.Add(labelY);
                    boundriesDict[labelY] = new List<SubPicture>() { label };
                }
            }

            boundries = boundries.OrderBy(b => b).ToList();
            
            var rowsWithItems = new Dictionary<int, List<SubPicture>>();

            foreach (var boundry in boundries)
            {
                rowsWithItems.Add(boundry, new List<SubPicture>());
            }

            foreach (var boundtyKvp in boundriesDict)
            {
                foreach (var boundry in boundtyKvp.Value)
                {
                    rowsWithItems[boundtyKvp.Key].Add(boundry);
                }
            }

            foreach (var item in subPictures.Except(labels))
            {
                if (boundries.Count > 1)
                {
                    for (int i = 0; i < boundries.Count - 1; i++)
                    {
                        if (item.TopLeft.Y >= boundries[i] && item.TopLeft.Y <= boundries[i + 1])
                        {
                            rowsWithItems[boundries[i]].Add(item);
                            break;
                        }
                    }
                }
                else
                {
                    if (item.TopLeft.Y <= boundries[0])
                    {
                        rowsWithItems[boundries[0]].Add(item);
                    }
                }
            }

            foreach (var row in rowsWithItems)
            {
                var checkedLabels = new HashSet<string>();

                var items = row.Value.OrderBy(i => i.TopLeft.X).ToList();

                var currentGroupLabel = items[0].Label.Replace("label_", "");
                checkedLabels.Add(currentGroupLabel);

                for (int i = 1; i < items.Count; i++)
                {
                    var current = items[i];
                    var currentLabel = current.Label;

                    if (currentLabel.Contains("label_"))
                    {
                        currentLabel = currentLabel.Replace("label_", "");
                    }

                    if (currentLabel != currentGroupLabel)
                    {
                        if (checkedLabels.Contains(currentLabel))
                        {
                            return false;
                        }

                        currentGroupLabel = currentLabel;
                    }
                }
            }

            var itemsNames = subPictures.Except(labels).Select(i => i.Label).Distinct().ToHashSet();
            foreach (var label in labels)
            {
                var labelName = label.Label.Replace("label_", "");
                if (!itemsNames.Contains(labelName))
                {
                    return false;
                }
            }

            return true;
        }