It is rare to find a template for any specific subject, the Google for "filemaker Commercial Real Estate Template"
Lists one or two - but they turn out to be less than adequate or pages with all the words on them.
Some templates that are worth looking at for design and the tables or modules you could use as a basis are
Data For Life
Starting Point 2
They are fairly complex and difficult to decode the setup method.
White Paper for Filemaker Novices is worth reading
The Computer Guy, Seattle