I would do your set up, within IS Boxer rather then Jamba too.

With IS Boxer, you have Keymaps, which are groups of mapped keys.
By default, you have Control, General and FTL DPS keys.

Control should only be mapped keys which you want to always be on, in ever situation.
Such as mapped keys which occur on character switching etc.

FTL DPS Keys, are mapped keys used for attacks.
These apply to every team.

General are mapped keys, which aren't attack keys, but also apply to all toons.

Most of the mapped keys you create, will go into General.
Because they will apply to every team you run.
If you make a single mapped key, you can have multiple targets and each do something different.
You could put the Shaman's into an "action target group" called Shaman, and use Shaman as the target.
And do the same for Mage or Priest.
And have the one mapped key do something different for each of those target, on the same keybind.
Then you can mix and match a lot, and have the one mapped key (maybe for Fear or Buffs etc) on a single keybind for multiple teams.

If you have mapped keys, which you only want to apply to a specific team and not to the others.
You should probably make a Keymap (a set of mapped keys), named after the team in question.
Assign it to the team (character set) specifically, and not to the others.

It might take a bit of time to set up.
But a lot of it is shared functions between all of your teams.