You can't or rather shouldn't compare the crew of the Enterprise: the Flag ship of the Federation with the Voyager. Only the top graduates of the Academy serve on the Enterprise, anyone else serves on all the rest. Sorry but it's like comparing the crew of the Queen Mary to the crew of a Carnival Cruise ship.
Yes, I can compare them, and really its more relevant to say its like comparing the crew of a modern day flagship with, say, a frigate or something. Theyre both instruments of the same authority, and theyre both highly prized in terms of technology, if not grandeur. The crew of the frigate might not be quite as good as the crew of the flagship, but they would still have had to go through years of training and experience in order to be trusted and relied upon with such responsibilities.
Tal Celest passed the Academy.
Had the same training and experience as Harry Kim.
Is she on equal standing as an Ensign on the Enterprise?
Even if they are just ordinary people, that doesnt invalidate the point Im making. The problem is that so many other people on the ship seem to be just as capable at engineering as her.
Who else but her, Harry and Seven did they ever show build something?
I recall O'Brian needing ALLOT of help getting DS9 to stay up and running. Sisko built the Defiant, that also trumps O'Brians skills and I also recall Dax having skills in Engineering too. LaForge often asked Data for help for almost EVERYTHING he did. Westly had ideas and created stuff LaForge never even dreamed of.