Used SDK test play mode and seems ghost can trigger TeamC, but are not blocked with TeamC.
I do have some confusion on exactly which team is ghosts and which is birb.
Going of the Trello card for Workshop Map Editor it states: LC: Custom Spawn Point support. Team A is Knights, Team B is Dragon, Team C is Birb, and Team D is Ghost spawn
Waiting inside the test play mode eventually has birb spawn at a TeamC spawn. While it walks is blocked by and triggers all volume teams, and while thrown gets ignored.
pretty sure the intention is that the blocking volume filters are for players only. The only reason that birb spawns on team c is so another “birb spawnpoint” item doesn’t need to be added. Birb isn’t actually on team c itself.