I used to live in an old granite tenement block in Aberdeen and know full well the circumstances the OP speaks of - no one owns the communal area and more often than not in the old building there is no factoring / maintenance contract in place. When something goes wrong or needs upgrading the owners have to get together and pay jointly.
This means that frequently the communal areas are in a state of some neglect. Sounds to me like the OP through his eventual actions has made the communal area somewhat safer than it was before he started. In any event it doesn't sound like its a proper fire alarm which is subject to regulations but a domestic smoke detector.
In my old building I replaced all the light fittings because none of them worked. I split the cost of the new lights with the neighbours and they were delighted with having working lights in the place rather than relying on light spilling out from the fanlights above flat doors. I'm sure some on here would have me in court for that - but I left the place safer than I found it.
This means that frequently the communal areas are in a state of some neglect. Sounds to me like the OP through his eventual actions has made the communal area somewhat safer than it was before he started. In any event it doesn't sound like its a proper fire alarm which is subject to regulations but a domestic smoke detector.
In my old building I replaced all the light fittings because none of them worked. I split the cost of the new lights with the neighbours and they were delighted with having working lights in the place rather than relying on light spilling out from the fanlights above flat doors. I'm sure some on here would have me in court for that - but I left the place safer than I found it.