How to diagnose huge temp files issues
It depends on what kind of temporary file it is. If the file is a temporary cursor (result set from a query), then you should be able to use Advantage Data Architect and associate the file to the user with the management utility (menu Tools / Remote Server Info); it should show up as an open table.
If the file is an intermediate file used during the SQL execution, then I don't think the file will show up in the list in the management utility. In that case, it might be possible to use query logging. I would think that a query that causes the creation of a 30GB file would take a while to run.
As far as improvements go that might help, it is hard to say without knowing what is going on. There are a number of performance improvements, but if a query is running amuck and creating a large temp table, it may do the same thing with a newer version of ADS.