test.cs

using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl())
{
    tx.Create();

    tx.FontSettings.EmbeddableFontsOnly = true;
    tx.FontSettings.AdaptFontEvent = false;
    tx.AdaptFont += Tx_AdaptFont;

    TXTextControl.Selection selection = new TXTextControl.Selection();
    selection.Text = "Hello, PDF/A!";
    selection.FontSize = 360;
    selection.FontName = "Celtic Garamond the 2nd";
    selection.ForeColor = System.Drawing.Color.Red;

    tx.Selection = selection;

    try
    {
        tx.Save("output.pdf", TXTextControl.StreamType.AdobePDFA);
    } catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }
}

void Tx_AdaptFont(object sender, TXTextControl.AdaptFontEventArgs e)
{
    if (e.FontName == "Celtic Garamond the 2nd")
    {
        e.AdaptedFontName = "Arial";
    }
}