prodigy command on custom model

For the textcat.teach command, can I do on a custom model (like the model I trained through ner.train) ?

Like this, can I replace the blank:en with my model name? Thanks.

Yes, excatly. The spacy_model argument can either be the name of an installed spaCy model or its path (basically, anything you can load with spacy.load()) or blank: plus the language code, if you want to start with a blank model.

In case you haven't seen it already, the recipe docs also include a more detailed overview of the built-in recipes, plus descriptions of their arguments and examples: