As great-grandchildren of a Sovereign (Queen Victoria) the children of the 2nd Duke of Albany were HH and (British) Prince/ss under the implied grant by the Letters Patent dated 30 Jan 1864. It seems to have been the view of the Royal Family and their advisers at the time that the 1917 Letters Patent revoked the royal and princely titles of those who did not fall within its provisions - thus HH Prince Alastair Arthur of Connaught then became known as the Earl of Macduff until his succession as 2nd Duke of Connaught (taking his courtesy title from his mother the Duchess of Fife). The LP's however contain a proviso "except those titles already granted and remaining unrevoked" - given Prince Alastair Arthur's titles had not been revoked it seems he was legally still HH and Prince but that clearly was not the view at the time. The same would apply to the children of the 2nd Duke of Albany. However if one accepts their titles were revoked by the 1917 LP's then they should be listed as
former princes and princesses of the Blood Royal:
Johann Leopold (d 4 May 1972)
Sibylla (later Hereditary Princess of Sweden, d 28 Nov 1972)
Karoline Mathilde (later Countess of Castell-Rudenhausen, d 5 Sep 1983)
Friedrich Josias (d 23 Jan 1998)
Ernst August Duke of Brunswick (d 1953) was (until deprived in 1919) HH and (British) Prince under the implied grant by the 1864 LP's (he is on your list) but his three sisters were HH and (British) Princesses as well. Two of the three survived until 1952 - Alexandra (later Hereditary Grand Duchess of Mecklenburg-Schwerin) d 30 Aug 1963 and Olga d unm 21 Sep 1958
By Letters Patent dated 17 June 1914 the following great-great-great grandchildren of George III were expressly granted HH and (British) Prince/Princess though they probably already had that status under the 1864 LP's (they were of course already HRH Prince/ss of Hanover):-
Prince Ernst August - on your list
Prince Georg Wilhelm (d 8 Jan 2006) as mentioned by Ivan above
Princess Friederike (later Queen of the Hellenes) (d 6 Feb 1981) who should also be on your list
(the further two children were born after the 1917 LP's)
The Hanoverian situation is complicated by the 1931 decree of the Duke of Brunswick that he and members of his family would bear the title Prince/ss of "Great Britain and Ireland" (an entity which had ceased to exist) but such decree has no legal effect in the UK and it is difficult to see how the late Duke could have purported to assume or confer British titles on himself and his family except insofar as they had been conferred and not revoked by the British Sovereign