Am I really going to state the obvious? Z movies like M3, M6, M7, M9, M11, M12 are all impossible in the main DB storyline, of which GT is a sequel of. M8 (the Broly film) makes no sense from a storytelling standpoint because Goku & Gohan are supposed to be SS if we are to place them sometime during the period before the Cell Games. Daizenshuu 6 outright speculates the timeline placement for each of the films, indicating that they are impossible within the framework of the main timeline. Toriyama says that they take place in a different dimension. Among other things, & if you can't see this, then you're being deliberately stubborn & illogical, & I can't help you.
Sigh. The same logic that ppl use to claim Buu saga SS3 Vegetto exists. Absence of evidence. I'll just go ahead & say then that GT Goku has gone through BoG & has absorbed SSG. Since there is nothing to disprove that, ofc.
If that is the logic we are going to play w/, then we can stop here & agree to disagree.
But anyhow. The only ones who will ever truly know the true timeline/history of the Xeno warriors are the Xenoverse team & the SDBH team. They are the ones who conceived them. Beyond this, it's all still speculation w/ some pieces of information to deduce certain events, & nothing is outright confirmed.
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And to clear things up about the translation. If you REALLY want to break it up, the primary keyword here is わけ or in Kanji form, 訳. According to a Japanese dictionary, it means "conclusion from reasoning, judgement or calculation based on something read or heard; reason; cause; meaning; circumstances; situation." When I say she says he looks younger, I mean she is presumably deducing it from her own experience. It is a subtle but strong way of affirming that this is not the same XVegeta she knows of, that this one is a little younger. There can be ambiguity if you're a master of reading too deep into it, but it is the narrative & there's nothing to suggest otherwise later on, not by XVegeta himself. So it is reasonable & safe to take her words as truth.