The UNKN does not mean the sim file is corrupt. There are a lot of those if a sim has cc especially. Do any of the sim files open in S3PE or do they all throw an error?
While we're waiting for someone who knows better what they're doing to come along, have you tried changing the .sim file's name to .package and putting it in your mod's folder? So, for example, take Dina_Caliente.sim and change it to Dina_Caliente.package and put the package file in your mods folder. Then see if it shows up in your library. That's the first thing I would try. ETA: Tried it. It didn't work.