You good. Timeline bad.
Arren Kae has baby Handmaiden. It's probably not a planned event and so could have happened when she was already in her 40s, assuming fertility is not all that different in the Star Wars Universe. No where does it say she was young. In fact, she was one of Revan's first Masters.
(10 years passes)
The council finds out about Kae's child and exiles her.
(unknown period of time passes)
Kae follows Revan to fight in Mandalorian Wars.
(unknown period of time passes)
Revan, Kae and Yusanis go to Malachor V where war ends.
(~4 years passes)
Events of KotOR I happen.
(~5 years passes)
Events of KotOR II happen.
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