ClinicalTrials.gov data includes BriefTitle, OfficialTitle, and Acronym elements to capture 3 types of titles.  The ResearchStudy Resource description suggests a ResearchStudyTitleType value set includes short, public, and scientific.

If using this value set, the addition of "official" and "acronym" codes would support data exchange for nearly 400,000 records in ClinicalTrials.gov

Alternatively the TitleType value set (created for Citation Resource) at http://build.fhir.org/valueset-title-type.html could be used, and "official" could be added to that value set.  If "public" and "scientific" have Definitions they could be added to the TitleType value set as well.