There's nothing really we can do other than just punish people who are reported with evidence. However, does this benefit anyone? Not really as if you start banning people or banning alts then your taking what little competition their is right now and basically telling them they're not welcome. Yes this is a problem and yes we need to address it but its a very tricky thing to address.
This response is pretty much the problem.
Reporting someone for not playing the game the way its intended is not and will not ever be considered harassment and no action will be taken towards a player doing so. So please don't "warn" other players thank you.
You can report players who are doing the same thing even if you don't get proof, then atleast if proof arises from other players or future trouble you can factor in the previous reports too. It also allows us to keep an eye on players who are accused to see if the report has merit or not. Although I can understand your frustration if only 1 party is being pointed at and not both but remember 2 wrongs don't make a right, I'm greatful you took responsibility though and stated a fair case for what happend and why.
If you're going to shine a light on a situation in game or a problem in game please provide the full story and not just cull out information because the other party is your friends, it makes your point lose validity.
How would you even fix something like this? You bring back unlimited kills just makes the problem easier, you take away kill score TW becomes just cap fest and then people just use alts to ninja recap. You force a pair of guilds to always be on opposing teams then what happens when a new guild pops out of nowhere, do they have to wait to maintenance for the rule to be changed so that its not whoever gets C guild automatically wins kinda ordeal. This situation isn't "Too much work to fix" its pretty much impossible to fix and still do right by the players.
So what can we do guys? Can you guys not just play nicely with each other? Can you guys not just enjoy Eden while its still around? Every server of the game is slowly but surely losing players, can you guys not just be respectful to each other or do we have to baby sit the game to the point that everytime people are being scummy we need to throw out punishment that in the end only hurts yourselves. We can add it the rules if you feel its the only way that people can actually get along