I think a warden plugin is extremely needed to combat the confusion and chaos going on where any CT is free to make any order and talk over any order. I'm going to try to cover most of the criteria fantastic provided, but I might also have to lightly skim over the topics of how a warden would control chat and how a player would get warden, but they will not be the main focus of my suggestions.
I personally don't think the aspects of warden should be controlled through a menu, mainly because I wouldn't want it covering 1/5 of my screen and being a major distraction and perhaps a burden on my gameplay. Instead, a warden could right click their knife or any weapon without a scope and aim at a specific spot on the floor to create or remove multiple, multicolored markers.
Ensure warden system is not being abused by the same people round after round.
1. Whether the process of getting warden is through a vote, queue, or some sort of ranking system based off stats, 8+ hours of playtime on CT side should be required to become a warden to ensure that a player is well aware of all the rules and knows how to deal with common scenarios that a warden would encounter. This would combat the fairly new players that are unfamiliar with the rules and would give them time to become more experienced and knowledgeable of what is and is not allowed
2. A player can not be warden two rounds in a row. Whatever the process may be to become warden, it should not allow a player that was previously warden to become warden the next round
Solve issue of chat orders going unnoticed and causing chaos on the servers
In my opinion wardens should always have a mic and should not be giving orders through chat and should be asked to give up their warden spot if so, but in the case of an absent mic, they should have a simple "[Warden]" prefix in chat and their messages should be in an easy to see, flashy color, such as red.
Solve issue of conflicting orders being given by multiple CTs
The whole purpose of warden is to have priority over all the other CTs while giving orders. Letting other CTs give commands is completely pointless because that is the exact state the server is in right now, where the person that talks the loudest gives commands and whoever tries to talk over them are just ignored. Warden should give orders until killed, where then another CT is chosen as warden and the cycle continues until the round is over. The other CTs job should be to enforce the wardens orders, not override them.
Solve issue of CTs talking over each other and Ts flooding voice chat
Whether it be through a command or a menu, The warden should have access to either temporarily mute Ts or CTs, but this should only be executed when the warden can not be heard, or specifically for when the warden is giving an order.
Other things I wanted to add
1. A command to give up the warden role such as "!quit"
2. Though its not necessary, there should be a leaderboard for the best wardens that just counts and displays how many rounds a warden has won without being killed
3. Since players can purchase skin colors with credits to make them appear red, or blue. A warden should have a different color than the rest of CTs to show that they are warden, and would help players focus on what their supposed to be looking at
4. A simple way to control markers for players to go to would to right click their knife or any weapon without a scope and aim at a specific spot on the floor to create or remove multiple, multicolored markers
