Please help with this puzzle

[Coqueta]

What's the order of the glasses filling up?

That must mean that there are no 'blocked pipes' and they are not in fact glasses but sealed flasks.

If they are open glasses only the lower group would fill - ie 7,6 and 3. Once 3 is full the structure would simply overflow.

It is a really crap diagram for the question.

Here is a diagram for which the answer is 7635421.
No pipes are blocked, all containers except 1 have lids with vents that reach higher than container 1.

That is the right drawing. The answer is intuitive and does not take more than a few seconds to work out.

The right-hand group is lower than the left hand group. Then within each group it goes from the lower to the higher. Simply because as you say all are sealed (except 1).

Not sure why we had a bollocks diagram to start with.

I agree