Are there criminal offenses outside of Title 10 that apply only to military members (i.e., that have a personal jurisdiction element similar to UCMJ)?
Answer: Yes. The following offense was created during the Reconstruction Era. My preliminary research indicates that it has never been litigated (there is certainly no appellate caselaw interpreting it).
18 U.S. Code § 592. Troops at polls
"Whoever, being an officer of the Army or Navy, or other person in the civil, military, or naval service of the United States, orders, brings, keeps, or has under his authority or control any troops or armed men at any place where a general or special election is held, unless such force be necessary to repel armed enemies of the United States, shall be fined under this title or imprisoned not more than five years, or both; and be disqualified from holding any office of honor, profit, or trust under the United States."