Yes, we can! Can you please submit a pull request here: https://github.com/certik/slabikar-otf, just add the new character definitions here: https://github.com/certik/slabikar-otf/blob/dce9fc9e575f7d6e..., here is an example how uring (ů) is done: https://github.com/certik/slabikar-otf/blob/dce9fc9e575f7d6e....