Why would you imagine that there hasn't been/isnt a 'review of support' going on? Quite apart from everything else, any student support professional, personal tutor, hall warden or anyone else who had any contact with any of these students will have been in agonies going through everything they'd ever done to see if they could have done something differently - when I was in this situation, I convinced myself it was all my fault and had to seek counselling myself to help me through it.
I have been in academia for over 20 years and I concur that there has been a substantial increase in students with mental health difficulties - and my role in Admissions tells me that in an awful lot of cases those difficulties do not develop at university. There has also been a substantial increase in student support, which, when I was an undergrad, was genuinely non-existent - both generally, in terms of personal tutoring and making time to talk to students, and specifically, in terms of help for people who are struggling or who have or develop mental health problems. One of the lessons that anyone working with people with mental health difficulties has to learn is that there is only so much you can do - if a student accepts help, or just is prepared to reach out and talk, a great deal of difference can be made, but if not, one is limited. And, as others have said, suicide can be contagious.
There may be things Bristol can do differently, or are already changing, but there may not be and it is not for us to judge - it is for the people within the situation, who are going through a hugely traumatic time and are probably doing more than enough blaming of themselves- we really shouldn't add to it.