Yan,
For me the "sweet" taste buds were the last to return (a year or so as I recall). I craved salads as soon as I could tolerate the dressing (it burned early on). Salt is usuually the first taste sensation to return - maybe he's just burned out on chicken noodle soup.

I couldn't stand Boost or Insure. I used Carnation Instant Breakfast instead - I guess you can substitute soy milk if you are lactose intolerate. The best flavor I found was the "Espresso" unfortunately you can only get it in the multi flavor packages so you'll be stuck with vanilla and stawberry as well. I always used a straw for drinking liquids, by the way, to direct where they went into the back of the throat. I would add some hagen Daz coffee flavored ice cream to pump up the calories.

By 5 months I was eating solid food. You really have to experiement a lot with different foods, tastes and textures (and keep repeating the experiments, it is a very dynamic and changing thing). My dogs got VERY fat during my early post Tx phase.

Maybe he should see a swallowing therapist.