Hi,
You can save seeds from your Kiwano( In case anyone else is wondering what it is, it is Cucumis metuliferous. It also goes by the nicknames- Horn Melon, African Horned Cucumber, Jelly Melon, and probably a few others I don't know, lol.) It does need to be fermented like a tomato. There is an outer casing that comes off the actual seed with fermentation.
About Red Currants, I'm not postive. I do know I get seedlings from my Jostaberry(currant-gooseberry cross) popping up in the spring. So I'm betting they need a cold period to germinate.
Remy