Without snooping on your files i can't help you any further than saying this:
- Take a peak at vanilla files (or the files from a mod that introduced a custom kingdom with custom culture) ... then compare them to your own in order to identify missing/misspelled entries.
- Make sure you have everything in the chain of xmls that might be needed ...(culture/ kingdom / clans in kingdom / lords in clans / lord equipment / settlements/ troop trees & troop details etc etc ).
PS. Set up your kingdom as a vanilla culture...if it works, you've narrowed down your issue.