Your site only says "words" or "complete words", it doesn't reference any dictionary. BRALL is a word, albeit an obscure one [0] that is not found in most dictionaries.
It's found in one dictionary. Last published in 1911.
Brall isn't an obscure word, it's an obsolete one. I think it's fair to say that if your word isn't in Oxford or American Heritage, you shouldn't expect it to be in the result set.
It feels as if you hit "BRASS" and "ZEBRA" then couldn't make it fit with "LL", then searched for "brall" hoping to have a hit.
But if you used WinAMP back in the day, you'd have whipped this one in the ass.
[0]: https://www.wordnik.com/words/brall