Teamoverlay shows your teammates' powerup status like Quad, Pent, Eyes.
It would be great if in CTF mode, it also showed if a teammate is carrying a flag and/or which rune.
Deurk told that if you add %R to this line:
hud_teaminfo_layout "%p%n $x10%l$x11 %a/%H %w"
it will print the rune you carry.
i didn't test, but it should display the rune's icon, not text.