I'm 99% sure your customizations to the INSPIRE profile web editor are the cause. Did you make a backup before customizing, if you need to roll back?
Anyway, I've seen these errors before after customizing an Profile for the editor. Here's the likely culprit: The metadata is validating against an XSD (the URL specified in /schema/xsdLocation of the INSPIRE definition.xml file). That shouldn't be a problem, right? Well, the XSD *only wants to see the metadata elements in the EXACT order* as they are written in the XSD URL. So, even if your custom INSPIRE is writing out all the metadata elements correctly, you will still see the errors provided in the starting thread because the XSD validation is failing. It's not a Geoportal issue, it's an XSD issue. And yes, it can be very frustrating.
The solution? Make sure the organization (tabs, etc) in your custom INSPIRE profile editor write the metadata elements out in the same order as the XSD. (or ... remove the XSD validation 😉