No, level_version(1) is just put at the start of the script once. See here.
I tried to explain before, but I'll do so one more time, because you're not getting the concept. Dungeon Keeper, in 1997 had level script. Lets call this script version 0, because programmers like to start counting at 0. Then decades later, KeeperFX came along and updated the script to a new version, with a few commands gone, several commands changed in function, and quite a few commands added.
Now KeeperFX can use both the old DK script, and the new KeeperFX script, but you need to tell the game which script you're using. You want to use functionality that's only there in the KeeperFX script, so you tell the game you want to use KeeperFX script by adding LEVEL_VERSION(1) at the very start of your script.
The upside is, now you can use all the new functionality. The downside is, you've got to convert the rest of the DK script to FX script. Luckily there's not many old commands that changed. However, the CREATURE_AVAILABLE has changed. So look at the KeeperFX script, read how the command works now, and change ALL INSTANCES of your script to work like that.
So, like this:
Code:
CREATURE_AVAILABLE(PLAYER0,SAMURAI,1,16)
CREATURE_AVAILABLE(PLAYER0,DARK_MISTRESS,1,4)
CREATURE_AVAILABLE(PLAYER0,TENTACLE,1,0)
Then, start your game, load the level. Exit the game again, and open KeeperFX.log to see if there are script errors. There it will tell you which commands are wrong now, also look those up in the KeeperFX command list, to see how you've got to change them. Be sure to click the links in my post.