Good Luck!
A GOLD MINE would be to see the INDEX of the "Negerat Gazaette"- the official Ethiopian Gazette (published in English as well as Aramahic and Geez'). It contains the relevant regulations -and continued publication through the Derg era. In the USA only ONE library has a full set and they don't lend it. I am especially interested in WHEN the victory medals were actually issued- because they often do not show up on WW2 medal ribbon bars.
If you can find ANY loose ribbons, or ribbon bars, please, please, please, please buy them. I will happily reimburse/pay a profit for them.
If you can- see if you can find a decent Derg "Hero of the Nation" medal (akin to a Hero of the Soviet Union). A bunch were awarded for the wars-esp. against Somalia and Eritrea and also Cuban and East German awards. Both countries had LARGE military/economic contingents in Ethiopia and there are all sorts of photos of Derg officers wearing Soviet/Bulgarian/DDR medals/ officer school badges.
BUT THE RAREST medal you are likely to encounter is the replacement DERG era "guerrilla medal"- it has a rounded bakers' bee hive oven on it with grenades falling out of it. The Sellasie era "guerrilla medals are rare enough- even though made by Mappin and Webb, but the Derg ones are incredibly, insanely rare. Most people do not know what they are .
GOOD LUCK!