I think it might be Galls. Galls is a plant's reaction to an irritant, usually some type of mites. Sort of like how an oyster will create a pearl around a grain of sand irritating it.
Since you are having an ongoing problem with new leaves becoming affected, then the irritant is likely still on your plants. Since mites are usually the cause of galls, you can try one of the natural, organic miticides on the market. I have never used any commercial miticides, so I can't recommend any of them.
I had this problem with a Ficus Benjamina. I used my 'Big Gun' spray on it and the problem stopped. If you would like to try my 'Big Gun' spray, mix a few drops of Dawn dish liquid, about a teaspoon of rubbing alcohol and distilled water in a spray bottle. I use this spray mixture to get rid of spider mites.
** As with using any spray on a plant for the first time, spray test leaf, wait 48 hours and check for any adverse reaction on the test leaf. **