The mercurial reminds me more of an ENFJ. The thing that stuck out to me as a major difference between ENFP and Mercurial type is the description of Mercurial types being able to distance themselves from pain and being able to stay busy. ENFPs, like their less-outgoing INFP counterpart, are brooders. An ENFP typically has some down-time, much like an introvert, to accommodate painful or negative emotions and see how they jive with their values (Fi). That integration process takes a lot of time, so having it as an auxiliary function demands that ENFPs experience and integrate painful feelings before switching to something new.
I typically see busyness as a coping mechanism in ENFJ. They are also strongly attached to romantic relationships, open to new things, and spontaneous. Butinstead of wallowing in and trying to make sense of their feelings, the ENFJ has a dominant Fe and is outwardly focused on others and in helping others, rather than on brooding.