Changing taxonomy labels is different than changing CPT labels - it uses a filter instead of an action - but is still very easy.
I didn’t change the ‘Portfolio Types’ taxonomy but I expect that it is not too difficult to do so as ‘register_taxonomy()’ has a similar action (called ‘registered_taxonomy’) with similar parameters.
I created a first draft of a website for a new client. It included a portfolio of their clients. The client feedback asked for the portfolio to be renamed to ‘Our Projects‘. I decided to change the ‘Portfolio‘ and ‘Portfolio Types‘ labels in the admin to reflect the front end change and to eliminate any confusion for the client when they update the projects section.
Action to a filter
While it is true that the register_taxonomy() function has a ‘register_taxonomy‘ action, changing the strings via that action didn’t work. In fact I got an error in the admin are that I no longer had permission to edit the ‘Portfolio Types‘ taxonomy.
I wrote code to write all the labels to the error_log. With that I could see the strings I needed to change to change ‘Portfolio‘ to ‘Project‘.
Admin UI Change
Full Code for CPT and Taxonomy
Putting the above code with CPT label changing code from the earlier post: