There are many accurate portraits of Marie Therese Charlotte as an adult still in existence; I'm refering to oil paintings, not engravings (which can be misleading):
----Two large full length portraits at Versailles. One in a white gown painted by Baron Gros in 1814. Another in the red gown we've seen on this site, painted about 1824, when she became Dauphine. These two portraits are in the Restoration Galleries, usually closed to the public. But I made special arrangements to see them in 2002.
----A half-length seated portrait in a gold embroidered gown painted by Robert Lefevbre in 1827, now in the City Hall in La Rochelle, France.
----The portrait by Baron Gros called "The Embarkation of the duchesse d'Angouleme", now in the Bordeaux museum.
---- Two portraits once in the Bourbon collection at Frohsdorf, sold at Sothebys in 1938: one half-length in a white gown, another one in a red gown painted by Thomas Lawrence.
----A portrait miniature painted about 1845, now in the collection of the Wurmbrand-Stuppach family. I saw this portrait (the only one I've seen of M.T. as an elderly woman) when I visited Countess Wurmbrand in the 1989 and 1992.
----There is also a wonderful full-length portrait of M.T. as a young woman, just released from the Temple, full length, dressed in black. One copy is in a Scottish collection, the other is in the Hermitage in Russia.
----It appears that she was never photographed, according to sources I've checked and correspondence I have received from the Bourbon family.