AoA,
Allah does understand every language. For that matter he understands our emotions, senses, thoughts and other unsaid things. But this does not mean that recitation, especially in prayers, should be done in languages other than Arabic. It also does not mean that recitation should be done implicitly by thoughts!
The Holy Quran was revealed in Arabic. One reason for this is that the immediately addressed people to whom Quran made the first contact were Arabs. But Quran is here to stay. It is not meant only for the Arabs. It is meant as the message of Allah for all people till the judgement day-all people of all languages and nationalities and regions and etc.
Languages of the world are not equal. What is said in a language can rarely be translated fully into others. The connotations, the moods, the implications of a sentence in a particular language can rarely be conveyed in other languages. For a ready example, a movie dubbed in another language seems hollow.
Hence, a translation is not and will never be equivalent to the substance of Quran.
We, the human kind, have been evolving languages for thousands of years. The evolution of languages was not in our direct control previously. But we have been in control for the past fifty years or so. I am talking about the mastery over the design of computer languages which are a subset of natural languages (remember Chomsky hierarchy). Even in that subset of natural languages, hundreds of thousands (if not millions) participants have designed or helped design hundreds of computer languages. All of us here on this forum have had exposure to computers and some exposure to computer languages. Yet can you say that all are equally suitable for a task? Even in this subset such a sweeping statement is inappropriate.
Arabic is itself nothing less than a miracle. Linguistics books usually contain a section on the phonology of all the world languages and another equally massive section on the phonology of Arabic alone. If you doubt me, go and consult a good linguistic book in the local library.
Hence, the true substance of the Holy Quran is only rendered in Arabic. There is no substitute for it.
However, as I said before, a translation helps in understanding when you do not know Arabic. But it helps in understanding only the aspect it was able to translate. And there is no language that can translate all aspects of one language into itself.
Actually, we don't even know what are the "all aspects".
Regards,
Worried.