Generator for mapping national alphabets to the Basic Latin

GenerateBasicLatinMapping.cs

public static void GenerateBasicLatinMapping()
{
    // https://github.com/anyascii/anyascii/blob/master/unidecode/unidecode.tsv
    var unidecodeLines = File.ReadAllLines(@"C:\Users\username\Desktop\Unidecode\unidecode.tsv");
    var outputFile = @"C:\Users\username\Desktop\Unidecode\toBasicLatin.txt";

    Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
    var encodings = new[] {
        10000, 10006, 10007, 10010, 10017, 10029, 10079, 10081, 10082,
        1250, 1251, 1252, 1253, 1254, 1257, 1258
    }.Select(i => Encoding.GetEncoding(i)).ToArray();
    bool isSupportedEncoding(string s)
        => encodings.Any(e => e.GetString(e.GetBytes(s)) == s);

    var additionalSupportedChars = new HashSet<char>();

    // Hangul consonant and vowels: 매니저 -> ᄆ ᅢ ᄂ ᅵ ᄌ ᅥ -> MAeNIJEo (manager)
    var jamos = Enumerable
        .Range(0xAC00, 0xD7B0 - 0xAC00)
        .SelectMany(ch => ((char)ch).ToString().Normalize(NormalizationForm.FormKD))
        .Where(ch => ch < 0xD000);
    //additionalSupportedChars.UnionWith(jamos);

    var latinRegex = new Regex(@"^[a-z]+$");
    var letterRegex = new Regex(@"\p{L}");
    var map = new Dictionary<string, string>();

    var originalMap = new List<(string Key, string Value)>();
    foreach (var line in unidecodeLines)
    {
        var values = line.Split('\t');
        if (values.Length >= 2)
        {
            var key = values[0];
            var value = values[1].Trim('\'');
            originalMap.Add((key, value));
        }
    }

    foreach (var (key, value) in originalMap
        .OrderBy(_ => _.Key.Normalize(NormalizationForm.FormKD) != _.Key)
        .ThenBy(_ => _.Key))
    {
        var decKey = key.Normalize(NormalizationForm.FormKD);
        if (decKey != key)
        {
            decKey = decKey[..1];
            if (decKey == value ||
                map.TryGetValue(decKey, out var decValue) && value == decValue)
            {
                continue;
            }
        }

        if (key.Length == 1 &&
            letterRegex.IsMatch(key) &&
            (isSupportedEncoding(key) || additionalSupportedChars.Contains(key[0])) &&
            latinRegex.IsMatch(value))
        {
            map[key] = value;
        }
    }
    var res = map
        .GroupBy(pair => pair.Value, pair => pair.Key)
        .OrderBy(g => g.Key)
        .Select(g => g.Key.ToUpperInvariant() + string.Join("", g.OrderBy(s => s)));

    File.WriteAllText(outputFile, string.Join("", res));
}