leif..I’m sorry but much of all that is a bit rambling, but I think you’re asking if an item of common property, to wit the handrail of an internal staircase, is illegal and therefore a safety hazard because it’s known to be non-compliant with current building standards / codes.
In my opinion the handrail would remain compliant if and until such time as the Owners Corporation undertook some works on its Common Property that affected it, such as replacing a section or perhaps raising the stairs (e.g. by re-tiling), whereupon the entire handrail would likely need to be made compliant (i.e. higher) concurrently.
That’s a bit rambling too, but suffice to say that if your Committee is aware of the safety issue, then compliant or not, it probably has a moral obligation to do something the lessen the risk (of someone falling) by perhaps installing an additional handrail above that existing or even by placing appropriately worded signage at/near the stairway; not advising that the handrail’s low but perhaps advising people to take care on the stairway and not to run whilst negotiating them.