First of all, to get a system which works 100 % correct is a dream.
Why? Because not everyone sees the same as a troll.
Example - we got a Ryze with Muramana which is normaly on an adc and ryze gets an Seraphs Embrace (dunno if this is the right name)
Now we got 3 possible options.
- He Trolls
- He doesn't know it better and clicked on the wrong upgrade
- He is trying an Hybrid build
We could say now that option 3 is a sort of trolling because why is he even trying it when there are very good builds already.
I guess the best example is akali at the moment because she was a full AP Snipe assassine the last seasons and today she is played as a offtank on top. If you would have played that in season 4 everyone would have flamed you and maybe called you a troll. Things changed, she got nerfed - i know that. I am just talking about what a character is for and what you build on him.
The next thing is champions and there positions. I get called a Troll from time to time because I play twisted fate as an ADC or bard in jungle. Sometimes it doesn't works and i get reportet for trolling, sometimes its working and nobody says even sorry for calling me that stuff in the beginning. But these are serious picks for me and i play them because i like the playstyle and i will do everything to win the game for me and my group.
Even if the report system was not automatic there would be different types of people which would say "this is a troll" while other would stay with "in which world can someone say this is trolling?" different types - different minds.
For your other questions about afk and full boots build:
People that are afk or even if they just run in a circle in base the system gets that and they will be punished - see different threads here in boards. Even if you sell all your stuff and buy just tears or boots and stuff this is recorded and gets detected by the system.
For AFKs you dont have to report, for people who just run in there base i would report them to be sure. The same goes for sell and buy useless stuff in the last minute - better report it to be sure.