There are two problems. One is with template import, and the other one is with host import. Here's how to reproduce them.
Templates:
Create a template T1, create a host H1 and link them together. On the host H1 create a regular trigger. On the template T1 create a trigger prototype and set dependency on H1 that trigger. Export templates and don't change anything. Try to import back. The import should fail.
Hosts:
Create a template T1, create a host H1 and link them together. On the template T1 create a regular trigger so the H1 gets a templated trigger automatically. Now create a host H2, but don't link it. Instead just create a trigger prototype and set dependency on that H1 templated trigger. Export H2 and don't change anything. Try to import back. The import should fail.