I needed to read your post three times to understand what you mean :)
1. an internal link to another question gets posted, like that: http://www.question2answer.org/qa/29743/edit-by-bothering-too-many-people
2. Instead of the link, in the post text it appears like: "Edit by" bothering too many people
What to do:
1. As Scott stated, you need a filter plugin. This has to check the text for http://yourdomain.com/
2. As soon as you find such an internal URL within the text, you need to extract the /postid/ (questionid)
3. Then you want to call the database and receive the title of the question.
4. Finally you replace the <a href="URL">HERE</a>, the HERE with the title.
Not super easy but possible in 2 - 3 hours, I'd say.