I’m really happy they’re allowing Reborn and Twinspell to come back (together) in G’sA. Perhaps there will be a card interacting with Invokes/Galakrond.

No, They is correct here. The pronoun “They” has 2 uses:

1: To refer to two or more people or things previously mentioned or easily identified.
2: To refer to a person of unspecified gender. (aka the enemy player)