It looks like some aftermarket suppliers/manufactures may have done that for their own personal agenda, such as to profit from it; however, doing so does not make it true. In fact it now adds confusion, especially since we now have a real 6th generation Goldwing.
Here is how wikipedia says it "Some retailers of aftermarket add-ons/replacements parts, group all GL1800 models into two categories. They describe all GL1800s made from 2001-2010 as "First Generation" or "1st Gen,"[97] while GL1800's made in 2012 or 2013 are described as "Second Generation" or "2nd Gen."[98] This is extremely misleading because, in terms of complete Gold Wing evolution, the GL1800 itself is actually the 5th generation."
When talking engine generation, yes this is the 6th gen. 75-79= 1000cc, all naked bikes. 80-83 =1100cc. 1980 was the first year Honda offered the GL with Honda line fairing/ saddle bags/ trunk. First gen body style. You could still get a naked GL. 84-87=1200cc. 2nd gen body style and 84 model year being the last year to offer a naked GL. 88-2000=1500cc. 3rd gen body style. Now it gets a bit interesting. 2001-2017 1832cc gen 4 body style, sort of. Same 1832cc engine with a bit of a body change in 2012-2017. So you have 2 body styles in the 1832cc series, hence gen 1& gen 2. Now onto the 1833cc= body style 5. For arguments sake we should most likely leave out the Rune and the Valks, the slight panel changes and comfort levels.