More speculation: If you are reporting posts that are old when you report them, your report may not be high on the priority list.
If you doing that they can marked also as unhandled and maybe you will get a message from a Global Mod as i have done that when i started.
Depends also on what you reporting.
Reports that are "unhandled" are not marked as anything. Reports in "unhandled" status mean that no moderator has taken action on the post you have reported. This could mean the mods have not had time to review your report, or it could mean that some mods reviewed your report and were not sure if they should take action or not. It could also mean that responding to your report requires research that the mod does not have time to conduct.
You are not going to be notified if a mod is not sure if action should be taken or not.