Unsoftened can be replaced by several synonyms depending on the context of the sentence. If someone is talking about a hardened heart, alternative words can include unyielding, unfeeling, stubborn, and inflexible. For concrete objects, one may use words like uncooked, undiluted, or straight. Unremedied, uncompromised, or unreconciled might also be good choices when referring to problems that have not been resolved or conflicts that have not been settled. Unmoderated, harsh, and unbending are other words that might fit this category. Ultimately, the correct synonym will depend on the intended meaning of the sentence in which unsoftened is used.