Putting whitewash or plaster on the truth represents ignoring the truth. AT: "you hide the truth with lies" or "you lie and ignore the truth" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Being a physician represents being a person who comforts others. Being of no value means that they do not know how to do what they should. AT: "you are all like physicians who do not know how to heal people" or "you all come to comfort me, but you do not know how, like unskilled physicians" (See: [[rc://en/ta/man/translate/figs-metaphor]])
They thought that they were saying wise things, but Job was saying that they would be wiser if they would stop talking. The abstract noun "wisdom" can be expressed with the word "wise." AT: "If you were to do that, you would be wise" or "If you were to stop talking, you would appear wise" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])