Which certification course is best for a Writer?

What form are the medical articles (including tables)? Do you make them (technical author), correct other people's work (editor) or prepare the articles for publication (typesetter)?

What form are the medical images? What app are they made in? Do you create the images (artist), add captions, or combine into articles (layout artist)?

You seem to be describing a job rather than the work in the job. Adobe don't offer general training for a job, but very specific training in how to use particular apps. So you need to start by knowing the apps that will be used. If you are hoping to train for a new career in general, Adobe don't have much.

You say a certifiation course. It is usually best to start with what the employer wants or needs than try to guess.