When I say 'rational' like that I'm just kinda talking about how the 'rational' has been privileged since the Enlightenment. The way science/scientific thinking has come to be synonymous (culturally) with 'truth'. i.e. scientific truths are taken to be absolute truths rather than the conventional truths they really are, and that something which does not express itself rationally is not expressing anything at all.
Like, clearly, music, religion, art (though it's undergone a sort of pseudo-rationalisation) and things like that clearly mean something beyond what we can explain rationally. They hold meaning which cannot be rationalised but they are seen as being (in this context) meaningless (not valueless, just that they cannot ... lead to progress (I've not said that well)).
(science is work, meaning, truth while 'art' (broadly) is play, entertainment, distraction)
So yeah, just there's been a cultural shift toward the rational and away from anything that cannot be explained in rational language, and that's a shame because there are meanings which rationality cannot express - so we're currently (to whatever extent) incapable of expressing them/exploring the possibilities they lead to.
And yeah, I agree that rational language and conditioning are intrinsically linked. And that non-rational languages, being less rigid/digital offer us (better/easier) ways of thinking outside our conditioning., just due to the nature of the language - they're so indexical that you're kinda making up/defining your terms as you go along. 'course, they tend to be semantically inxact so you have to go to rational language to nail it down but I believe the thoughts/ideas will necessarily originate in the non-rational.
So we just need a counter-enlightenment.