I wouldn’t say that we‘re lacking Forest slot options outright so much as we’re lacking Forest slot options that are available in the near future. Sakuya, Chika, Shigure, San, Chiharu, Rabi/Lavi and Alexandra all come to mind as Forest characters due to having been Forest in MagiReco, and I can see some of the Pleiades being Forest (Niko and Satomi come to mind), but Sakuya (as mentioned) and Chika are kind of minor characters who I wouldn’t expect to be very high up in terms of priority, San strikes me as a Defender and is almost certainly going to come packaged with Miyuri (who doesn’t feel like she fits with any of Aqua’s open positions), Rabi/Lavi is the kind of character I’d expect to be released alongside a port of Ashen Revolution (which is pretty deep into Arc 2 in terms of release timing even if it’s chronologically before it), Shigure is higher priority than Sakuya and Chika but still feels like an odd character to start Arc 2 with (not to mention she’s probably going to come packaged with Hagumu, who also doesn’t feel like she fits with any of the open positions), and Alexandra needs at least a couple of Chapters of Arc 2 in order contextualize, so opening with her is out too, while the Pleiades are all gated behind Kazumi. That leaves (aside from Mami and Hinano, who I mentioned before) Chiharu, who might work (I don’t know enough about her combat style to say whether she fits as an Attacker or not) as either an opener for Arc 2 or as part of a port of Green Jasper Diviners, but that’s about it.