Ops, seems like I should have looked at my sources before I posted and not write stuff from memory.
You´re correct, at the time of the expedition La Belle would have been a 'barque' (i.e. just fore-and-aft rigged on the mizzen, a topsail on this mast would have probably made her a frégate légère, just as G. Grieco described her in his article in the Journal of Nautical Archaeology).
He, I'm german, nitpicking is part of my DNA
Well, in the Med wind conditions and directions can change quite drastically over a short period of time, so people tried to adapt to get from point A to point B as fast and efficiently as possible. Some favoured lateens, some square, some a mix of both. If both points are in the Med, than lateen sails may be the better option, if one of the points is on an atlantic coast with it´s longer 'static' wind conditions, than a mix might be preferable.
And if you look at the med section of Du Pas' book I linked above, you´ll find quite a few french fore-and-aft rigged vessel