Just a couple of quick notes on my own experience. Because I master batch everything is literally room temp when I make my soap. It does not cause any problems with soft soap. Soft soap is usually caused by too much liquid or an oil like hemp which will keep it soft for quite a while depending on the percentage used. You don't need to heat your oils back up, I promise you. There is no way you should have had to stick blend for 10 minutes so it also makes me think that your lye measurement was off and you didn't use enough. This would also make for a soap that won't set up.
Layering - there really is an excess of coffee in there and it could have caused the separation. You can wait up to another day before pouring the second layer without separation because of the heat generated by the soap for saponification melts the top layer of the first layer of the soap beneath it to help it adhere. Think about those beautiful soap cakes we all admire so much. They are unmoulded before the piping is done so the soap is at least a day old.
I just wanted to clarify those 2 misconceptions.
You could rebatch by chunking it up in small pieces and either using a crockpot or the oven, whichever suits you best. A bain marie will also work if you can put one together that is big enough to hold your soap.