They currently say unavailable because the area transition logic is not fully implemented yet and there's some extra checks that need to be done to make the bot work the same as if you used an area with a waypoint. For example, if you wanted to bot "The Wetlands" (old Pools and Streams), but have not already touched the "Ancient Seal" quest object, the bot would not do that for you yet, and you'd get stuck, since it blocks the way to the exit.
You can, at your own risk of the bot not fully working the right way, bot in most areas that don't have a waypoint. Just select them anyways, and start the bot. Fellshrine is an easy case, because the waypoint in The Crypt (old Church Dungeon) is right next to the area transition for Fellshrine. The bot will be able to get to Fellshrine and bot there normally just fine; as long as you withdraw TP scrolls and don't check take waypoint back to town! If you don't have the Crypt waypoint, it will then try to use Crossroads, since that area is the next area to travel through to get to Fellshrine. However, there is no logic that says "move to where Fellshrine should be" yet, so the bot explores Crossroads until it finds the Fellshrine area transition.
There is an area pather that will try its best to travel to the grind area through other zones. The only obstacle from it not working the way it should, is quest state. If you start a new character, you can bot from Twilight Strand -> Mudflats/Fetid Pool, but not Lower Submerged, since you need to complete the quest first. If you don't have a waypoint for an area, but you have all the quest stuff unlocked to get there, you can select that area, and the bot will (try its best) travel to it.
The last thing to note is that while the bot is traveling through other areas to get to the grind area, looting doesn't quite work the same. If it can loot something in range, it will. However, if combat pulls it out of range, and the area transition is in view, it will take the area transition before going back to loot.
All these things are being worked on, but for now, it's easier to just tell people to use an area with a waypoint and leave the options "unavailable". You can try other areas if you want though, just watch the bot a few runs to make sure it actually gets there before afk'ing.
Also related to the areas, boss farming is not implemented yet, because the bot has to take specially named area transitions to the boss room. This also requires some changes in exploration logic, because the bot can mark those areas as ignored because it can't find a path to it. All these things are being worked on, but the priority right now is getting everything properly updated and working before new features are added.
