The remote seems to have firmware upgrade. Hopefully that is not the limitation.
I would propose rather than codes, if possible, they could just create a learning app for the box that programs the power and volume keys. That way no-body has to worry about code support. Simply program the power and volume keys for each user's particular situation using your existing remotes.
For my situation I would like power to be TV and box, and volume to be my amplified speakers (Edifier). If we are allowed to program the remote then there are no brands to support, and it is a better long term solution.