I'm not sure what you mean!
Are you asking about Mdina or about Malta Decorative Glass? Different companies.
Both were quite haphazard in how they were finished. At Mdina, it depended purely on whether or not somebody was available to do the work required and how much new stock was needed in the very busy shop.
Less is known about MDG, I can only tell you how the few bits I have are finished. Several have fully polished flat bases. Several have round, ground pontil marks, I've not seen a polished round mark - yet.
I also have two bits where the base has been flattened on a marver, and a maltese cross prunt mark has beeen stuck deep into it. This cross is not the same shape as the Mdina Maltese Cross prunt - the "arms" of the cross have a v-shaped end, while the Mdina prunt arms are flat ended.