Phenomenology conít
There may be grammatical forms in a language, for example the forms in Athabaskan languages, to do with motion and time, that may indeed be difficult for a speaker of Indo-European languages to grasp.
Yet, even in these cases, the difficulty of translation relates to unfamiliarity, not to any seeming intrinsic incomprehensibility.
Learning to use words and grammar presents one kind of problem; learning the meanings of words and the intentions of grammatical devices presents another.