I agree with those that have said an experienced "harness technician" should be the one to use the harness with your daughter.
It takes more than just brute strength to use the harness correctly. The "handheld" one (or as my rink refers to it, the "fishpole" harness) requires some technique and knowledge on the part of the user for it to be effective. I would ask the coach about their experience using the harness as even an experienced coach may not be experienced in harness work.
At our rink, there is one coach who is the designated harness coach and its not something that's just passed around for anyone to use. In fact, my understanding is that it is considered a "skill" that some rinks will seek out if they lose a coach that has harness experience.
As for people who don't like the harness - some of it may be personal preference and some of it may have been who was operating the harness. I saw a coach using it in an almost Peter Pan-like fashion, lifting the little skater improbably high and for a long duration off the ice, and it didn't appear to help the skater either rotate or get a spatial awareness of the jump because it was clear the skater wasn't really doing the work. When my skater has worked in the harness, it was explained to me that they were using it with his axel to prevent both a "bad" fall during the learning process and to give just a "tiny" bit of help, if necessary, to help build confidence and learn the timing. In other words, consider it like "spotting" by a coach in gymnastics - there to provide safety and physical support where needed to learn the skill safely.
If its been a year working on 2T, I'd say give it a shot so long as you are confident in the coach's experience with the harness.
ETA: I think its normal for skaters to have jumps off-ice first but not yet be able to do them on-ice. When you think about it, the technique is not *exactly* the same and you are usually wearing sneakers off ice. My skater can do a 2T off ice pretty well but can't even come close on ice yet.