I do not have an independent feel for the word "allegorical" so I looked it up in a number of dictionaries, and I don't think it captures the meaning. Also, "precise" is not precise enough
to capture the Arabic word. I suggest "ambiguous" and "definitive."
I like "definitive" a lot, but not "ambiguous." "Ambiguous" leaves a negative impression. I consulted the thesaurus and found among its synonyms "cryptic", "doubtful" and "dubious!" The word is the exact opposite of محكمات
which literally means controlled or perfectly designed thus they have one indisputable meaning. Since we're choosing "definitive" for that one, maybe we can use "indefinite" for متشابهات
? The word literally means "carry multiple meanings", which Sarwar used in his translation.
Let's try to find a word or a short phrase that means the same thing. One such word is "equivocal" which the dictionary defines as ambiguous by design, which is what we have here, except that it is mostly used in a negative context as in deception. I just don't know of any word that means "carry multiple meanings" but in a positive light where the intent is that all the meanings are intended and valid, not meant to confuse of deceive.