I found that the tag midas refers to two different products: a tool of the Delphi world and a tool of the Mozilla platform. I just cannot create new tags because my rep is too low, so I'd like to know: where should I ask for someone to separate the tags and, once I am here, could someone from here do it?
where should I ask for someone to separate the tags
Right here. This is a problem that crops up once in a while and doesn't really have a good solution.
Someone has to go through the list of questions with that tag and manually retag them. There's no automated function that can intelligently detect which product the question with that tag actually refers to.
Looking at the documentation you link to, it looks like the simplest possible option is to create a midas-server tag for the Delphi-related product and continue using the midas tag for the Mozilla tool.
Someone here on Meta reading this question will have both the patience and the requisite privileges to create new tags. (Fortunately, there are only 12 questions this time. It shouldn't be too arduous.)