Documentation of the /*[VARIABLE]*/ feature in bookmarked queries can be confusing to someone not well versed in SQL. I eventually figured it out, but the important missing bit of information was this:
The string that starts with "/*" and ends with "*/" is actually an SQL comment, and the query you are creating must be valid and error-free with this string completely removed. I know the current documentation suggests this, but I found the explanation very unclear.
Thanks for your suggestions.
Fixed for version 4: https://github.com/phpmyadmin/phpmyadmin/commit/a01ca2920683c96118a0ec7c2c2e6b0ebb6aace5