Index misscalculation issue

private static void ApplyLocalizationParamsInternal(ref string translation, _GetParam getParam)
        {
            if (translation == null)
                return;

            string pluralType=null;
            int idx0 = 0;
            int idx1 = translation.Length;

            int index = 0;
            while (index>=0 && index<translation.Length)
            {
                int iParamStart = translation.IndexOf("{[", index);
                if (iParamStart < 0) break;

                int iParamEnd = translation.IndexOf("]}", iParamStart);
                if (iParamEnd < 0) break;

                // there is a sub param, so, skip this one:   "this {[helo{[hi]} end"
                int isubParam = translation.IndexOf("{[", iParamStart+1);
                if (isubParam>0 && isubParam<iParamEnd)
                {
                    index = isubParam;
                    continue;
                }

                var param = translation.Substring(iParamStart + 2, iParamEnd - iParamStart - 2);
                var result = (string)getParam(param);


                if (result != null)
                {
                    var paramTag = translation.Substring(iParamStart, iParamEnd - iParamStart + 2);
                    translation = translation.Replace(paramTag, result);

                    int amount = 0;
                    if (int.TryParse(result, out amount))
                    {
                        pluralType = GoogleLanguages.GetPluralType(CurrentLanguageCode, amount).ToString();
                    }
                }
                
                    index = iParamEnd + 2; //<== HERE : when the first parameter replaced, the size of thw word changed too so it should be recalculated
            }

private static void ApplyLocalizationParamsInternal(ref string translation, _GetParam getParam)
        {
            if (translation == null)
                return;

            string pluralType=null;
            int idx0 = 0;
            int idx1 = translation.Length;

            int index = 0;
            while (index>=0 && index<translation.Length)
            {
                int iParamStart = translation.IndexOf("{[", index);
                if (iParamStart < 0) break;

                int iParamEnd = translation.IndexOf("]}", iParamStart);
                if (iParamEnd < 0) break;

                // there is a sub param, so, skip this one:   "this {[helo{[hi]} end"
                int isubParam = translation.IndexOf("{[", iParamStart+1);
                if (isubParam>0 && isubParam<iParamEnd)
                {
                    index = isubParam;
                    continue;
                }

                var param = translation.Substring(iParamStart + 2, iParamEnd - iParamStart - 2);
                var result = (string)getParam(param);


                if (result != null)
                {
                    var paramTag = translation.Substring(iParamStart, iParamEnd - iParamStart + 2);
                    translation = translation.Replace(paramTag, result);

                    int amount = 0;
                    if (int.TryParse(result, out amount))
                    {
                        pluralType = GoogleLanguages.GetPluralType(CurrentLanguageCode, amount).ToString();
                    }

                    index = iParamEnd - (param.Length - result.Length) - 2; //TODO: This calculation is fixed, index calculation was wrong after replacing

                }
                else //TODO: wrapped with else
                {
                    index = iParamEnd + 2; 
                }

            }