Searching COCA for barnburner (no space) yields another 27 hits.
I must be reading it incorrectly, I count only five.
COCA, the Corpus of Contemporary American English, not COHA, the Corpus of Historical American English, which has only 5.
(You can’t compare the numbers across the corpora.)
The blunder is similar to a typo, one reads what one writes but misses the error. I read what you wrote but assumed and missed the one different letter; it’s so aggravating. Thank you for the correction.