Well, Ronin appeared on many covers with the rest of the Avengers roster before her/Echo's debut in #11, so I'm guessing yes, for example #7. I don't have the issues at hand, but Wikipedia says she decided to stay in Japan to keep an eye on the Hand.
> Okay,I understand that, but is my question this...The character (be it "Ronin I" or "Echo")is not listed as having been an Avenger, so was her membership official? Look at the roster in the Avengers-Earth's Mightest Heroes web site (which is pretty complete), there is no mention of her. Perhaps this was an oversight.
> Well, Ronin appeared on many covers with the rest of the Avengers roster before her/Echo's debut in #11, so I'm guessing yes, for example #7.
As I'm sure you know, covers are often symbolic and not reflective of the interior of a comic. Echo/Ronin was brought along to Japan, but there was never anything in the text to indicate that she was being offered membership (in fact, most of the team didn't even know her identity at first, whereas they all knew each other's identity). I think she probably would have been made an official member if the events of Civil War hadn't intervened.