Q. I can't find criticism of William Blake's works in EBSCO, can you help?

There are quite a few articles on Blake's works in EBSCO. One thing that might help is to search all EBSCO literature related databases at the same time. You can do that from the All Literature Databases tab in Working with Literature libguide or the Literature tab in Databases libguide (links below): select All EBSCO Literature Databases.

Don't forget to also try Literary Sources (also available from the links below). There are quite a few articles on Blake's works there as well.