How many container designs were tested? Between 11 and 17 there were 6 landings. Did they notice the problem on 11?

It's an interesting problem. The sample container will have to hold the external pressure out and, depending on the container temperature, deal with condensation around the seal.

Not if their container sealed properly.

My thought exactly. Couldn't they settle this with an isotope analysis?

In the article it states that the cross contamination arguments applied to the nasa rocks because the astronauts couldn't get the lid back on the sample containers. There could be contamination of the Russian samples, but the same argument about containers being improperly sealed doesn't apply unless there is some sort of evidence that it should.