I normally use 80% CO, 15% OO and 5% castor for my salt bars and they lather just fine. I think the lard might have helped keep it from hitting instance trace too. It was still relatively thin when I poured, just thick enough to keep the salt suspended which worked great for my cavity mold.
I did a experiment once, made a 100% PKO salt bar and it had 0 lather. Was like trying to wash with a piece of plastic, really weird. I definitely will report back on these bars.
The salt bars I made with neem and pine oil have improved a great deal too. At first there was very little lather, it was extremely thin and watery. Now it lathers like a normal salt bar should. I need to move it into the shower to see how they do on my skin issues.