I have found that there is an "Ubuntu Support Team" at https://launchpad.net/~ubuntu-helpteam but I am not sure it's official or active.
Please note that I am not referring to bug fixing support, I am referring to the broader OS support, with people available to engage users needing support with a problem and drive it to a proper resolution.
Is there an official team for this purpose with a clear scope and activity plan ?
It would appear the "Ubuntu Support Team" that you mentioned has been inactive for over two years. (In fact I don't think it was ever really 'active').
There are four main places to go for community support:
You might want to take a look at When should we use Launchpad Answers and when Ask Ubuntu. In my opinion none of these four tools are great for "troubleshooting", but this site is doing a very good job answering a lot of the questions people have about Ubuntu.