The real problem is located by not enough playerbot get invited for battleground requirements.
For all BG I made, only 8 bots get invited, for some BG it's fine but for other, it's time out cause the area is made for 10c10 or 15c15 (Arathi bassin, Deepwind Gorge, Eye of the storm) players(bot).
And it's like there is a script that say no more than 8 playerbots on each side will join.
Atm if you get inside those 3 BG 15c15 you'll get timed out, cause 8 player(bots) is not enough for 15c15.
For solve this issue, it could be great to random invite more playberbots than 8 by Battleground, maybe by getting info directly in battleground_template table.
For sure, you could use world.conf to change the setting and remove the time-out, but it's not really fun, some battleground area are empty since they are made for a biggest players(bots) team.