Note however that when I use it the extra bots always end up on the allied side. Not sure how it happens or why so I play with axis and it's like 1 of ours against 3-4 of theirs depending on what number of bots you have selected and this increases the difficulty especially on maps where you are the attacker. But it also feels more authentic on maps you are defending.
I'm not SP expert, but as far as I remember BF2 had hardcoded limit of 48 bots or something like that. You could the then use bot ratio slide (in game) to set percentage of bots being in Team 1 (in FH2 Team 1 is always Axis, Team 2 is always Allied). Thanks to FH2 Launcher you can overcome that limit and set any amount of bots you like, but due to BF2 limitation you can only end up with 48 bots in Team 1 by setting bot ratio to 100. To make teams even you will need to set overall number of bots to 96. Anything over that numer will end up with 48 bots in Team 1 and the rest in Team 2, so it should be possible to add more attackers on Omaha for example, but it won't work for maps where Germans are attacking, like Fall of Tobruk. Not sure about it, I may be wrong, I never played with more than 48 bots, you need to experiment with the bot ratio slide.
Note: bot numer and bot difficulty/skill set in the FH2 Launcher overrides in-game settings for both Co-op and singleplayer in local game. You can try launching dedicated local co-op server too, use FH2ServerLauncher in your Battlefield 2 (or Forgotten Hope 2 if you use standalone version) main installation folder. But that's just another can of worm, and settings work different there again I think.