To my understanding, the H&S sign offs of a maze include:
-LTC signing off before the maze opens to the public (and, I believe, before actors are allowed to even rehearse in the space). Like with rides, that has to happen every year.
-Tech team do daily sign offs: they'll check that all the effects work, the area is safe (ie, no nails poking out, no loose flooring, etc) and so forth
-Sign off from the Entertainments team, ensuring there's enough staff, all areas that should be locked are locked, all fire exits are clear, see if there's any potential hazards which may have been missed, etc.
As has been said, if a problem arises, it should be flagged immediately to someone working at the maze or nearby. That way it can be checked by actors / staff and appropriate action can be taken (Benin's right in that it's basically only tech/maintenance teams who can use a hammer). Actors should also look out for these things, but they don't always notice them immediately given everything else they have to do as well.
It's the same with a roller coaster imo: if you were to catch yourself on a belt buckle which somehow has a sharp bit, for example, it would be something you should mention. Staff should also look out for that but it's not something they would necessarily spot immediately given how many other things they have to do too.
Don't quote me on this, but until you get quite high up, I don't think there's no specific qualifications you need. Obviously, standard experience and courses you can take to learn how to write risk assessments, understand H&S investigations, etc, which are advantageous to have prior to being in those roles, but there's not formal qualifications required. Going higher up you need them (stuff from IOSH), though most people will undertake those qualifications whilst in a H&S in the first place as a way of stepping up.
I guess this is the major discussion point. Mazes naturally receive a lot of wear and tear at an accelerated rate. In the space of a group of 15 people, you can go from a nail being firmly in place to sticking out ever so slightly. And that can progress slowly as each group goes through. Of course the park has a duty of care and is responsible for whatever happens, but at what point should a line be drawn and we can rationally say 'The park aren't in wrong'? Or - to circle back to where this discussion stems from - how can we rationally say it's "horrendous that these things aren't checked"?
Not that there's a clear cut answer to either of those questions, just musing..