It is an adventure, and will be for quite a while depending at what point of treatment he is at, areas radiated, and dosage amount, but taste will eventually come back, maybe not quite what it was, but can be close. I'm not familiar with the potassium salt substitute, but have used organic salt substitutes, but not during treatment due to offending tastes of many foods, and not wanting to be turned off by any in the future, I avoided many, and relied on canned nutrition. Anyway, trying to improve saliva may help taste, drinking milk replicates saliva, and may help with eating irritating foods, but the lactic acid may burn in some. Umami, 5th taste sense, is unique, and transcends into all areas of the mouth, tongue....taste buds, which are more compartmentalized in taste senses for salt, sweet, sour, bitter, and helps with taste, so I use Umami type foods often...anchovy, Worcestershire sauce, hard cheeses, dry bonito flakes, fish sauce, dried mushrooms, soy sauce, cured meats, etc., which enhances everything.