A glance at the building values in use in UK/IE shows what you’d expect at the top - yes is at the top of the list, followed by house, and then a bunch of largely sensible other values. However, there are 117 pages of values, and if you sort it alphabetically you can see that quite a few are just misspellings.
I’m not saying here that building=farm_auxiliary and building=agricultural are the same thing (whether they are or not is an argument for elsewhere). But agricultural, agricutural and agriclultural surely mean the same thing, as do lych_gate, lychgate, lych-gate, and lich_gate.
Other kinds of typos are terraceqr, outbuildingq, substationq, garageq - someone was clearly trying to add a building and square it - in those cases it’s obvious what the person adding the building was trying to do. There are lots of examples where the words in the building type occur both with an underscore and a space (for example church_hall and church hall) and also with non-OSM capitalisation (community_hall and Community_hall).
There are some odd values with concatenated keys in them, including at least one with adverts in an HTML comment in the key: building=yesgateway_dining_facility_<--_this_content_was_made_by_yourforcesupport.com_-_powerful_websites_for_the_modern_force_support_squadron_us_forces_-->_https://www.100fss.com/gateway-dining-facility. I’m guessing that that’s nothing nefarious and just an unfortunate copy and paste faux pas. In another one, I really don’t want to know what was going on when this was added:
