I think and unfixed floating floor is exactly what it saya it is – it sits on top of the floor and hadn’t been drilled, screwed, glued ot otherwise attached.
The difference a by-law would make would be that it would ascribe responsibility for repair and maintenance of the floor to either the lot owner or the OC. The insurer would base their response on that.
If it turns out that the floor is not common property and your insurer refuses to cover the damage, you need to make a claim against the neighbour through your local court, if need be.
By the way, I notice Strata Community Australia no longer carries the “Who’s Responsible …” document on their website.
Along with the demise of their excellent online training program for strata committee members, it’s another reason you might want to rethink your membership of the strata manager body’s Owners section and move to the independent Owners Corporation Network.