I'm using fcom and have a few issues. Some bandits turn green when killed. I've noticed that a few items (including a horned helmet) are usable but don't actually appear. How do Iknow which mod has problems??? Please help!

Please install MMM correctly....

Read the readme and you'll figure out what you did wrong.

Your far better asking in the FCOM thread if your topic concerns that particular mod.
Independent threads tend to lead to well intentioned but often confusing and incorrect information.

Look for FormID finder on TESNexus.

You've obviously not followed the very detailed instructions in the opening post of the FCOM home page.
Green bodies = an incorrectly named BSA.