It is my understanding that 33mm and 23mm lunar medals made by Shenyang Mint during 1881-1992 are copper (brass) only. Shenyang Mint did not have the capability to produce gold and silver plated coin until 1992. Therefore, IMO, most Shenyang Mint lunar medal sets (silver, gold and silver plated) in the market place were produced after 1992 either by Shenyang Mint or private mints.
Based on the pictures posted, the surface texture of the medals suggesting this set is silver plated. I was not aware that Shenyang Mint had produced 1984-1995 lunar medal set as you mentioned in your post. There are three series of luna medal sets produced by Shenyang Mint; 1981-1992 (33mm, 23mm), 1993-2004 (40mm, 33mm, 30mm) and 2005-2012. Something is very wrong.