That O’Malley should viciously renders these youths as having committed a crime against “good character” thus amplifies how reprehensible and sinister these incidents were.
There are two variations you could have here. Your original sentence is fine, but the structure of 'That the author does X demonstrates Y' is a thing that a lot of people wouldn't use because of their internal grammatical systems. It's technically fine and I've used it before, but it can sound a bit odd sometimes, and you don't want to overuse it because it's a very noticeable kind of structure.
eg. if you saw two guys on a train wearing jeans and black hoodies, you wouldn't think twice, but if you saw two guys wearing purple and orange jester hats with jingly bells and slippers shaped like cow heads, your brain would probably register that repetition. Reusing basic sentence types is like wearing jeans and hoodies, but the 'that X showcases Y' thing is more like a jester hat + cow slipper combination, so just be cautious with it.
The alternative, which Falling Star has used, would be to say 'O’Malley viciously renders these youths as having committed a crime against “good character” thus
amplifying how reprehensible and sinister these incidents were' which is also fine.
Regarding event/events: this kind of gets into distinctions between whether a collection of related occurrences count as one 'event' or a series of 'events' (ie. if you played tennis and basketball after school last week, did you play 'sport' or 'sports?') It's pretty open to interpretation as both are grammatical - by instinct I'd go with the plural and say 'the events should not be repeated,' but 'event' is possibly more technically accurate in this instance. I wouldn't worry about it though; when we're only dealing with 200 word analyses it's easy to get into semantic quibbles, but when teachers and assessors are reading through hundreds of thousand-word responses, they just breeze through this stuff and ignore anything that isn't apparent on a first skim-read, hence why clarity is so important.
Re: mark out of ten, I have consulted my magic 8 ball and concluded that this is a 9.17459/10. But again, this is maybe a fifth of what you would realistically write in an exam, and no essay maintains the exact same numerical level of quality throughout. Typically, an essay would have certain sections worthy of a high mark and others of a low mark, so this excerpt might sit at a 9/10 level, but it could either be a high point or a low point depending on the rest of your discussion. That's why holistic marks are a bit hard to apply here since writing at a 7/10 standard for tasks like this doesn't necessarily mean you'll be scoring exactly 7/10 in full practice essays. It's probably more helpful to think of things in terms of 'my analysis is at a 9/10 standard, but my expression is at a 6/10' or something like that. If you're going to use quantitative measures, then apply them to qualitative components of your essay
