My take on it. :o)

You could use "lacking" instead of weak, but I found that a bit too much - no comunication at all doesn't seem to be what the text implies.

There are several ways of saying it. I have worded it this way to suggest "break down" and "poor" as other ways of translating the thought of the original.

You could also say, "Communication between them is poor..." and use "inadequate" or "poor use of resources" in the second part of the phrase.