How the chatbox visually looks, and how the player interacts with it has not changed much over the years. Command lines are shoehorned into the same functionality. WIth jj2+ becoming bigger and bigger and with more commands and shortcut oddities, it can get quite daunting.

Autocomplete for commands.
Commands can be difficult to remember. The current chat box is 1 line, and last chat of 8 lines above it. When starting Chat with / to start your command, moves the 8 lines of last chat up-to 5 upwards to show 5 autocomplete answers, alphabetically on available answers left. So it should look something like this:

Player1: Hey
Player2: Hey
Player1: How goes
Player2: Things go well
Player1: I'm testing the chatbox
||Player1 captured the flag
2 minutes left...
Player2: Cool
/addadminip <group> <ip_address>
/addallowedcommand <group> <command>
/addblockedcommand <group> <command>
/addprivilege <group> <privilege>
/admingroup <group> <on|off>
Command: /a

5 seconds later.....

Player2: Things go well
Player1: I'm testing the chatbox
||Player1 captured the flag
2 minutes left...
Player2: Cool
/allowready <on|off>
/allowmouseaim <on|off>
/allowsuicide <on|off>
/allowwalljump <on|off>
Command: /allow

5 seconds later.....

||Player1 captured the flag
2 minutes left...
Player2: Cool
/allowready <on|off> - Toggles the availability of the /ready command
Command: /allowr

So preferably when one command remains, it takes the description truncated to the first sentence.