I think one of the most important changes made in pandoraFMS5.x is adding "Agent custom field" base filtering to "monitor detail" page. actually that feature extended the usefulness and usage and of customer fields.As i understood there are some problems arise when we tried to add devices to multiple groups. (as eg: device type, Ownership) but we can use customer fields to create various kind of groups. we can add devices to groups and the we can use customer fields with ids to categorized them to any kind of sub groups. so as a request I think you should add this feature to agent detail also. because it could be more useful because custom ids are mainly go with agents rather than modules.
My next request is simple one "add pagination to bottom of monitor detail page" it is useful when you want to move next result set without scrolling back to top of the page.