There is an autoicon template in Template:DLC Icons
{{DLC Icons|Unnatural healing}} and {{DLC Icons|Darklight brazier}} produces Unnatural healing 
and Darklight brazier 
for example.
But because pages rarely change DLC status, and templates consume processing, we generally just do it manually outside of things like templates and automated lists.
I'd love to have something do it on the backend so that we didnt even need a template at all, and links would be automatically tagged but I don't have the knowledge or access to implement that (we may be able to talk to Zesty and omac about it if we did have solution ready to go)
But yeah saw your edit summary and wanted to let you know the current state of that issue.