You know what they say; if you keep changing the product but the results are the same, it's probably you.
I ve heard that coco coir is an amazing medium for growth and yield but is lacking in the taste department. YOu say that clones from the same plant act differently in different environments. That should tell you right there that it's not the plants. Like someone else said, get back to the fundamentals. Your soil, nutrients, lights source, your water and your air. If you can, try to mimick your outdoor grow as best as possible, and if your water smalls like sulfer, you're probably gonna need to use that R/O system or at least find a way to collect the rain water.
I'd bet for sure that it's your water, nutrients and medium in that order. Use pH'd r/o water. Get yourself some quality organic nutrients and make sure that includes some kind of beneficial bacteria like Great White Shark, Humboltd's Myco Madness or Advanced Nutrients Voodoo Juice. I get the idea that the sulfur is doing some funky stuff to your medium and the biota within. And maybe thing about switching to another soilless mix like ProMix or Sunshine #4. Most smokers seem to agree that bud grown organically in live soilless mix tastes the best. At the very least, take care of that water situation. I bet it has something to do with the water that messing up your nutrient balance. Good luck and don't give up
PS
Flowering/flavor enhancers aren't necessary when grown right, and anyways it would only be a band-aid over your problem. You should get to the root of why this is happening.