There are number of problems in methods of Usermacro related API calls:

(1) it returns array of hosts regardless of user parameters
(2) processing of template related macros is incorrect (no processing of templateids), the code is absolutely broken

All code of usermacro.get must be reviewed.

Note that calls to usermacro.get must be reviewed and fixed in template.get, host.get and other methods when (1) and (2) are done.