Usually if you're doing a tlist_sql query on a PowerSchool custom page, any SQL query that actually works in SQL Developer will work on the custom page.
I found an odd one today, though—if you have a SQL query that actually works in SQL Developer that uses course names (e.g., ((course_name='Name of One Course') OR (course_name='Name of Another Course'))), that same query will just die silently on a PowerSchool custom page.
On the PowerSchool custom page, you have to use the course number instead. You cannot explicitly call the course name.
Update: Someone brought to my attention that the course name search should work in tlist_sql, but there may just be a character encoded weirdly. Very true, very possible. I'd still probably go with just searching by course number, since that's less likely to change than the course name.