So I worked for about 2 1/2 hours today with the black MiniMAD and came across this while working because I was having the same problem. No control over OSC and no documentation or support available online. So, I thought I would come back and share my findings with you.
I'm not positive, but I think you can only cue "Cues" and "Scenes" by sending OSC to madmapper. In madmapper, under help there is a list of OSC commands that can been sent. However, I think when uploading the project to the miniMAD, all you are uploading is your surface, projector settings, and media. Which leaves you with very limited control (only the commands listed in the miniMAD user guide).
IF you can send all those OSC commands listed in madmapper to the miniMAD as well, I was unable to do it through OSC from medialon. This is because medialon also sends a value with the OSC address. SO, I used UDP instead of OSC. This allowed me to send "/play", "/pause", etc. in a frame without a value attached, and that worked for me. So maybe try sending the OSC address through as a UDP packet instead of OSC. Use the same 1111 port.
also, /set_media_by_name/{media name} & /set_media_by_index/{media index} should set the media to be played but I would assume you would the need to also send the /play command after that. So, maybe send the set command and then the play command and perhaps that will play the selected media.
I may be able to help a little more if you let me know what software you are trying to control your miniMAD from.
Hope this helps!
Cheers!