The Mool Mantra is composed of nine adjectives that define the nameless. There is no noun. It makes sense because what is being described is indescribable.
Further, there are no verbs, no pronouns,
no predicates or subjects. This is what makes the Mool Mantra especially mysterious. It does not conform to any grammatical laws of the world. It is free from the bonds of language and grammar.
There is no apparent rhyme either; although I have found some beautifully syncopated hidden rhymes in the mantra. This enhances the mantar's mystery, and magnifies its magic and meaning.
The magic and mystery is lost when we translate portions of the mantra by saying "God is one" or "He is the creator" or "His name is truth" or "His name is true." We are making a lot of assumptions in such translations. Even "God" is an assumption. "He" is a bigger assumption. As soon as we say "is" we are interjecting our will on the ultimate doer. We are adding a finality that does not exist.
In all such descriptive translations we are losing the vastness of the mantra. Who are we to say that we are talking about "He" or "She" or whatever? Who are we to ignore "You"? Who are we to ignore "I." Who are we to put labels with affirmative is's? Who are we to ignore the universe of possibilities.
The best translation for the mool mantra I can think of is the most minimalist translation. Here is another attempt after meditating on the mantra:
One Vibration (or One Force, or One Om)
True identity (True name)