Are i-Quants overrated?

We all know modern "intelligent" Quantization that uses an imatrix to make a Q4_K_XL model to feel like Q6_K. But here is what i notice: While this works well on most English tasks, the effect can be reversed on other languages or niche tasks. The reason is quite simple and you will find out quickly when you look in the imatrix-file: You find 80% English here with mostly basic tasks and some code. Few imatrix files are thoughtful engineering work.<