If its not one of the validated level two tags then level three must be used to avoid biocheck message. == Research Notes == is a validated level two tag == Research Note == is not a validated level two tag Level two includes: == Biography == , == Research Notes ==, == Sources == and == Acknowledgements == Common level three tags are:
=== Early Life === === Family === === Occupation === === Death & Legacy === === Timeline === === Disputed Origins === You can make virtually any level three tag that you feel is appropriate
"== Research Note ==" should be "== Research Notes ==" (with an 's').
There are only four permitted level-two headings. == Research Notes == is one of them but == Research Note == is not. However, === Research Note === would formally be permitted as a level-3 heading (though it wouldn't be sensible to use it). That is why BioCheck says the level is wrong: level three would be correct for Research Note (in a narrow technical sense), but level two is wrong.