I can request to have my PhD certificate name a more specific research area than "PhD in Computer Science". What should I have it say? I have already been enrolled in a PhD program and published a couple of papers. When I eventually get the certificate, it will state that I have a PhD in Computer Science. However, I can submit a request to change that to whatever I find more appropriate. I am asking here to be better informed before I raise the issue with my supervisor.

My research paves the way for machine-learning based solutions to be used for solving a particular software engineering problem.

I find (PhD in Computer Science) too broad of a description and (PhD in Software Engineering) too narrow. I also find (PhD in Artificial Intelligence OR Machine Learning) not to be an accurate description of what my thesis is actually about.

Should I, for example, use (PhD in Applied Artificial Intelligence) or (PhD in Applied Machine Learning)? Other suggestions will be appreciated.
Many employers and recruitment agencies use either automated searches or low skill human readers to select resumes that meet specific requirements. Only those resumes will be viewed by a human with knowledge of the job etc.

If you pick an unusual subject designation for your PhD you risk your resume not being selected for jobs that require a PhD in computer science. It may never be seen by anyone who understands that "Applied Machine Learning" is just as appropriate for that job as "Computer Science".

If your resume passes the filter it will be read by someone who can evaluate your specialization from the text and the publication list.