Well, I decided to take a weekend off, and I return to a hailstorm of botafumerio vs botafumeiro - yes there is a difference in the spelling, but somehow, I was confused as well and originally used the "botafumerio" spelling, only on the breadcrumb trail at the top of the page, and the url of the page itself. I stand corrected, as I got it wrong.
In my article, I meant "botafumerio" as the Spanish spelling and botafumeiro as the galego (Gallego) spelling. There is indeed a difference, and I failed to get it right in the article, which is now corrected.
To clarify, I am by no means an expert in either language, but I do perform a lot of research before I write. If you google "botafumerio" and put this spelling into the search, you will find a multitude of websites/references with this spelling, including this Spanish translator:
https://www.spanishdict.com/translate/botafumerio. You must put the spelling into quotes or google will default you to the search for botafumeiro, the apparent galego word. Because of this, I would lean on the side that this may be the actual and only correct spelling of the word, whether Spanish or galego.
There is a multitude of people who got it wrong, then, if indeed there is no such word in Spanish as "botafumerio" and I was only following what I thought was correct. But it would be very, very nice if anyone actually knew, as a language expert in both languages what the correct words are!