We have gone over this a thousand times.
1) Jeremy obviously did not realise how serious things were and
2) the Bambers liked to keep Sheila’s illness hush hush
Jeremy obviously thought ringing the local police might be more discreet
You haven't read the questions properly. I will rephrase them to aid clarity...
If Sheila was the killer, and she had already shot someone when Nevill called Jeremy:
1) Why did he not phone 999? (it had already gone beyond trying to keep it hush hush)
2) Even if he phoned Jeremy, why didn't he say 'Sheila's shot your mother!'
If Sheila had indeed gone beserk and held the weapon..
3) Why didn't she shoot anything other than people. i.e. why not blast a window, or a wall too as you might expect in a fit of rage?
4) If she had not already killed when Nevill called Jeremy, then surely her 'berserk' behaviour would have disturbed others, yet the evidence suggests not. Any explanation?
5) With the exception of a fight with Nevill, there killings have all the appearances of a quite deliberate close range act, which is at odds with the randomness of a mentally ill young woman going 'berserk'. Why?