Really obscure commands like that usually require manufacturer formats for the commands. You know whether Roomie will accept a friendly format because instead of "Parameter 1" the command will say something friendly like "Volume" and give you a placeholder value – which it will not do with these kinds of side commands. Also, "VOLUME UP" is just going to move it up, it doesn't set a specific volume or have any parameters, you need to use the actual SET commands to set the volume. Sliders require a recognized format (Roomie needs to know what the min and max are), so a generic command like this wont work for that.
First, make sure you're using the modern Onkyo control set. You can see this in the device list if your device says "All Models Zone 1" instead of the older "All Models IP Zone 1". The new one is the default now for all auto-discovery and everyone was migrated automatically by 2.0.X, but there may be stragglers.
Second, you will need the appropriate command. For instance .CENTER LEVEL SET and .SUBWOOFER BASS SET. These take special parameters defined in Onkyo's public documents. Note that while SUBWOOFER VOLUME UP is there now and works, .SUBWOOFER LEVEL SET we just found to be missing and we'll add that shortly.
Onkyo defines the .CENTER LEVEL SET volume format as “-C”-"00"-"+C". Those are hex digits and that is what you'd enter as "Parameter 1" in Roomie. Meawhile, .SUBWOOFER BASS SET is "-A"..."00"..."+A". And so on. For detailed listings of the thousands of possibilities, best to consult the Onkyo documentation.
Thank you.