We have not updated the image above showing the various categories of El Nino. While the transition to using ERSSTv4 did change designations of strength for some events, overall the changes were not drastic when it comes to the image in this blog post. 

To answer your last question, no we have not added a "very strong" category. The categories remain three monthly averaged ONI values as follows:

> 0.5C - Weak

>1.0C - Moderate

>1.5C - Strong