Not to throw another kink into the discussion, but Valse Venezolano No. 2 as arranged by Diaz, is written as (3/4 6/8) right at the start.
Yet, it arguably plays better, accent wise, when played as 3/2 across two measures.
Don't know if that is also the case with No.3 (Valse Criollo).
So, I don't think the markings in this case are always strict rules, other than, it has to sound good!
