WiethoofdThe arena mode stuff can be replicated on a local server, make sure to have sv_pausable 1 and pause the server, even recording a demo should make the element show up so you can find it with vgui_drawtree
The thing is, it's seemingly impossible to replicate AFAIK. The best way I know of would be, creating the arena server, joining spectate, adding bots, then joining a team mid-round.
However, adding bots to the server immediately throws me into the game, regardless of whether I chose "fight" or "spectate." So therefore the most reliable way to get that panel to show up has proven to be impossible.
I mean, I might try and record and play back a demo to see if it shows up, as a last-ditch effort.