Apple uses Universal Type Identifiers (UTIs) to identify file types. These identifiers form a hierarchy. A JPEG file is thus not only of type public.jpeg, but also of type public.image. This allows for the creation of groups in Tembo.
When you create a file however, you only specify a file name extension. The application owning that file type needs to provide the system with the matching UTI information.
When no UTI is found, a dynamic UTI is created and assigned: dyn.someGibberish123
By default, Tembo excludes files with a dynamic UTI. These are mostly system files of no interest to most users. You may remove this exclusion in Tembo > Preferences > Advanced.
My assumption is that Filemaker failed to provide a UTI declaration for their plug-ins. This would explain why they are not showing.
Other users have reported the same issue with Adobe InDesign files. Hence the option to configure exclusions.
Houdah Software s.à r.l.