Apparently the closest widely known language to Hungarian is Finnish (see here). Unfortunately, SQL Server FTS does not seem to support Finnish either (see here).
You always have the option to create your own word breaker and word stemmer and load it into SQL Server FTS. For more information on how to do that for Hungarian, see this SO post. Of course, doing something like this would be a signficant undertaking, but I think there may not be any better options out there.