I'm not so sure about the irrelevance of language. Language makes up our mind, or at least has an strong influence on it. Unfortunately, meanings and concepts change, no matter if words are preserved. And on account of it, I'm afraid we can't be sure about what undertestood Muhammad while hearing, for instance, the word "qalam" or "hajj". Sometimes, I wonder if I should "pray" in silence, triying to beg pardon for my sins, to thank God's mercy and to clean my soul.
Nevertheles, I pray in Spanish, but I'm learning arabic -thought I'm pretty sure I'll never ever be fluent!!