Okay I fully believe Cal is 18 in JFO, not any younger and not any older.
Cameron said that Cal was part of the “status quo” aka the Jedi Order for the “first 13 years of his life.” There’s not a set age for younglings to be chosen by Jedi, so I just roughly assume he means that Cal has been part of the status quo since he was a baby.
JFO takes place 5 years after 66, so that would make Cal 18 when he leaves Bracca with Greez and Cere.
I personally like to believe that JFO extends over a period of six months, because while playing the game and reaching the end, I feel like Cal didn’t get enough time to bond with Greez even though Greez really cared about Cal in the end. Besides, their lives could not have only consisted of planet hopping and little conversations here and there. They’ve gotta sleep every once in a while, and Greez talks about making meals for them which we only see once.
Bonus: since Jedi Survivor takes place 5 years after Jedi Fallen Order, that makes Cal 23 in my book (the same age as me by the time it comes out in 2023!).
