That's an interesting solution to the problem of translation (how do I know if I've got the meanings of the words right?) you've got there: just measure what's going on in the respective participants' brains! ;)

There are two reasons why you might not want to work at this level. Firstly, thinking about translation again, if I were translating the language of an alien species, their brain-equivalent would probably be sufficiently different that looking for neurological similarities would be hopeless. Secondly, it's just easier to work at a higher level of abstraction, and it seems like we've got at least part of a system for doing that already: you can see it in action when people actually do talk about meanings etc. Perhaps it's worth trying to make that work before we pronounce the whole affair worthless?