Meditation as devised in AA’s Big Book is concentrated, directed thought at a higher level than the material world.
If you want to incorporate Buddhist, other eastern, or other forms of meditation and contemplation, go for it. But you don’t have to, in order to comply with AA’s suggestion to meditate in the sense in which it was intended by the authors. Our job is to understand what the writers of the Big Book meant when they wrote it, and the above is what they meant. Adopt other practices in addition to not instead of the above.