GREAT SULTAN

'Great Sultan' is one of various informal titles such as ''Grand Turk'', used to refer to the Ottoman Sultan, known in Ottoman Turkish as ''Padishah'', ''Hünkar'' or ''Hakan'', the sovereign of the Ottoman dynasty.
More appropriate would be to use the style Sultan, or rather Sultan of Sultans (''Sultan us-Selatin'' in Ottoman Turkish or ''Sultan es-Salatin'' in Arabic), one of his many official titles.
Like Great Khan (but there the usage is so frequent since centuries that is can be considered an established convention) instead of ''Khagan'', such translations fail to properly render the subtle complexities of the original phrases.
A curious circumstance is that the Ottoman dynastic tradition was to give the style of sultan (elsewhere a Muslim ruler) to male and female princ(ess)es, merely as close relatives of the ruling Padishah, without an appanage (as the empire was indivisible). So the western fabrication could at least have had some logical merit if those has been rendered as, say, junior sultan, but that is not the case.