I am a little younger than T&V but old enough to remember it happening. I studied this as a case study whilst at university (post grad) however and remember being asked about the case and given various media interpretations and then being asked as a group who thought that T&V had been mis-treated: nobody did. At that stage we were given case files to study and every single one of us changed our minds by the end of it.
The issue for me around if they should have been tried as adults is not in any way about if they should have served a shorter sentence or been treated more leniently, but simply at 10 years old they did not, and would not have had the capacity to understand what was happening in terms of a trial. This is irrelevant of their personal background, no 10 year old would have the capacity to understand the complexity of the crown court system, no matter how idealic a background they had, in fact many adults don't understand the system process but the difference is, it is reasonable to expect an adult to seek out the information about the system, what to expect, an adult is able to seek out representation that they feel is going to best meet there needs. These things are not reasonable to expect of any child, so therefore these things had to be provided/chosen by others (adults) in the case of T&V. That's not to say that the representation and guidance they had wasn't good- simply an acknowledgement that they were not able to gain this for themselves because they didn't have the capacity to do this for themselves because they were children, and therefore to put them through an adult system was intrinsically unfair. The issue that really needs to be looked at is what system should be put in place to enable a fair system for the trial of children, and this is also true of children committing much more 'minor' crimes.
In relation to their ability to understand right and wrong, my opinion is (as was found and enabled them to be tried in an adult court) they did understand what they were doing was wrong. What I am not sure of is if they understood the actuality of how wrong it was. Both T&V were exposed to vast amounts of age innaorpriate material, the extent to which they were abused can be debated, however I've never heard anyone try to claim each boy had any adults providing a strong moral compass giving consequence for their actions, they weren't regular school attenders so family life was the norm for them. This included a lot of very violent films and video games, one claim was that these images were being acted out in the horrific acts against poor little James, and I wholeheartedly believe both boys knew this was wrong, I even believe that V more than T(who has some learning difficulties) knew that such acts would end up killing James. I'm not completely confident that they both understood (again particularly T) that death meant gone forever.
I honestly don't believe there is an easy answer, I think serious questions need to be asked of the justice system without the emotional hype. Locking up and throwing away the key T&V isn't really justice for James, it's just 3 lives lost instead of 1, and I can't imagine anything will really bring solice for the Bulger family and the loss of their dear boy- even if we re-introduced the death penalty, so perhaps the best thing we can do is look at what justice is, what it means, and how we can best serve the victim and the perpetrator when it comes to crimes committed by children. A system where there can be no question of if the trial is fair of a child, can be the best justice for James at this stage, and I'd welcome this to happen in James name to really honor him, so that his suffering was not all in vain.
For what it's worth, I do think V should be incarcerated for life now, he has acted unthinkably as a child and that's one thing but he has had an awful lot of therapies and support as well as money spent on him and he had proven himself to be a continued risk. In that instance he should be removed from public life.