Distance to landing
This was always a bit fuzzy. Whilst the 225 does like quite a flat approach especially when landing hot/heavy, we eventually decided that the diagram you referred to was really about the required landing distance in the event of an engine failure / running landing. If you follow the profile as it seems to be shown it is ridiculously flat and places you poorly if you have an engine failure.
My suggestion therefore is to ensure you have the necessary space available but don't actually use it all up normally - so there is a bit left if you have to convert to a running landing due to OEI after LDP. What the official answer is, who knows!
Certainly in reality on line flights, no-one stuck to the very shallow profile, and there seemed no point in trying to enforce it.
Regarding the attitude triggering an exceedance, the problem lies with your monitoring programme, not the pilots. A programme shouldn't force pilots to do things a certain way (and in this case, risk landing too long) just for the sake of it. Such a programme should only be to detect habits where safety margin is reduced below normal. So the event might be > 10 degrees near the ground (say, below 15'), but at 50' clearly there is no danger of a tail strike and the event would more sensibly be 15 deg.