All true.That's actually consistent with her backstory from Legends; she was a Jedi Initiate who was smuggled to a safehouse on Belsavis, and captured by Inquisitors after that safe-fortress was breached.
(Note that while the Inquisitors didn't really take a center stage role until Star Wars: Rebels and are thus often thought of as Disney-canon, they actually date back to Kevin J. Anderson's Young Jedi Knights series of the 90s.)
Edit: Also note that Ismaren's backstory is *way* darker than it was probably intended to be, because it means that she became the Emperor's consort and then subsequently an Emperor's Hand when she was *in her early teens*. She was explicitly trained as a Hand *before* she had her son, she was eighteen *then*, and unlike Mara Jade who was canonically mostly used as a top-level messenger, Roganda was explicitly set up as a seductress and assassin.
Man, if Leia's kidnapping nets the Empire the Jedi underground safe-house network, Third Sister's scheme and Kenobi's action could blow open and endanger a lot of Order 66 survivors and Force sensitive children.
And yeah, Ismaren's story is all kinds of fucked up from beginning to end, and I had not made the age-of-induction connection before.