Question: Who was the last Holy Roman Empress and requested a name day celebration that was completed in August 1803?

Context paragraphs:
Constance, Queen of Sicily: Constance (2 November 1154 – 27 November 1198) was Queen regnant of Sicily in 1194–98, jointly with her spouse from 1194 to 1197, and with her infant son Frederick II, Holy Roman Emperor, in 1198, as the heiress of the Norman kings of Sicily.  She was also Holy Roman Empress by marriage to Henry VI, Holy Roman Emperor.

St. Francis Mass: Michael Haydn completed the Missa sub titulo Sancti Francisci Seraphici, Klafsky I:23, MH 826, on August 16, 1803, apparently at the request of Empress Maria Theresa for a name day celebration.

Beatrice of Swabia: Beatrice or Beatrix of Swabia (April/June 1198 – 11 August 1212), a member of the Hohenstaufen dynasty, was Holy Roman Empress and German Queen in 1212 as the first wife of the Welf emperor Otto IV.  She was also the shortest-serving Holy Roman Empress, dying three weeks into her marriage.

Maria Theresa of Naples and Sicily: Maria Theresa of Naples and Sicily (6 June 1772 – 13 April 1807) was the last Holy Roman Empress and the first Empress of Austria by marriage to Francis II, Holy Roman Emperor.  She was the eldest daughter of Ferdinand IV & III of Naples and Sicily (later Ferdinand I of the Two Sicilies) (1751–1825) and his wife, Marie Caroline of Austria (1752–1814).

Beatrice I, Countess of Burgundy: Beatrice of Burgundy (1143 – 15 November 1184) was a Sovereign Countess of Burgundy from 1148 until her death, and a Holy Roman Empress by marriage to Frederick I, Holy Roman Emperor.  She was crowned Holy Roman Empress by Antipope Paschal III in Rome on 1 August 1167, and as Queen of Burgundy at Vienne in August 1178.

Maria Josepha of Bavaria: Maria Josepha of Bavaria (Marie Josephe Antonie Walburga Felicitas Regula, 20 March 173928 May 1767) was Holy Roman Empress, Queen of the Romans, Archduchess of Austria, Grand Duchess of Tuscany, etc. by her marriage to Joseph II, Holy Roman Emperor.  By birth, she was a Princess and Duchess of Bavaria as the daughter of Charles VII, Holy Roman Emperor, Elector of Bavaria, and Archduchess Maria Amalia of Austria.

List of Holy Roman Empresses: Holy Roman Empress or Empress of the Holy Roman Empire is the title given to the consort (wife) or regent of the Holy Roman Emperor.  The elective dignity of Holy Roman Emperor was restricted to males only, therefore there was never a Holy Roman Empress regnant, though women such as Theophanu or Maria Theresa of Austria, who controlled the power of rule, served as de facto Empresses regnant.

Adelaide of Italy: Adelaide of Italy (93116 December 999), also called Adelaide of Burgundy, was a Holy Roman Empress by marriage to Holy Roman Emperor Otto the Great; she was crowned as the Holy Roman Empress with him by Pope John XII in Rome on February 2, 962.  She was regent of the Holy Roman Empire as the guardian of her grandson in 991-995.

Maria Amalia of Austria: Maria Amalia of Austria (Maria Amalie Josefa Anna; 22 October 1701 – 11 December 1756) was Holy Roman Empress, Queen of the Germans, Queen of Bohemia, Electress and Duchess of Bavaria etc. as the spouse of Charles VII, Holy Roman Emperor.  By birth, she was an Archduchess of Austria as the daughter of Joseph I, Holy Roman Emperor and Wilhelmine Amalia of Brunswick-Lüneburg.

Elisabeth Christine of Brunswick-Wolfenbüttel: Elisabeth Christine of Brunswick-Wolfenbüttel (28 August 1691 – 21 December 1750) was Princess of Brunswick-Wolfenbüttel, Holy Roman Empress, German Queen, Queen of Bohemia and Hungary; and Archduchess of Austria by her marriage to Emperor Charles VI.  She was renowned for her delicate beauty and also for being the mother of Empress Maria Theresa.  She was the longest serving Holy Roman Empress.

Supporting paragraphs: St. Francis Mass Maria Theresa of Naples and Sicily
Answer: Maria Theresa of Naples and Sicily