i believe its a nutrient issue or fertiizer issue - can't remember which one though. those leaves will never be smooth but still work just fine -

I have a tropical that its looking like this too. leaves are bumpy looking. some are turning yellow. I looked on hibisicus dr. but didnt see anything like it. I didnt fertilize in aug due to rains. did you fertilize yours?

i searched some more on hvh. a guy had bumpy leaves and he said it was a magnesium deficiency. he used epsom salts and it improved 80%. said the leaves were bumpy and curling.