In addition to recognizing the default DITA topic formats: topic, task, concept, reference and composite, topic specializations can also be edited in the Author page.
The content completion should work without additional modifications and you can choose the tags which are allowed at the caret position.
The CSS styles in which the elements are rendered should also work on the specialized topics without additional modifications.
The toolbar/menu actions should be customized to insert the correct element names if this is the case. You can go to the DITA document type from the Document Type Association page and edit the actions to insert the element names as specified in your specialization. See this section for more details.