Well I am not sure to have fully understood the discussion in german language about this topic
Anyway about the question:

Is the universe finite or infinite ?

The critical point is not, in my opinion ,the supposed quantity of mass \ energy rather its geometry

we normaly assume that :

a) a 3d infinite universe can not have a border
b) a 3d finite universe must have a border

on the contrary topology explains that there is a third possibility

c) A finite 3d universe without a border
If you travel to one direction , sooner or later you get back to the origin

It is impossible to figure out altenative "c" but it has been proved to be a reality

As far as I know , most of the scientists , nowadays beleive in a finite but borderless universe