I would argue that 92 keyboards are well within the "Vintage" era of keyboards. Mechanical switches were prevalent, though PC prices were on the decline and everyone was buying them, there were still many very well made keyboards.
In my opinion, a Vintage keyboard would refer to anything using older manufacturing methods, but was also made some time ago. It's tricky with computers because they are fairly recent technology whereas a vintage typewriter would be considerably older.
Vintage definitions that could be used for Keyboards:
–adjective
9. representing the high quality of a past time: vintage cars; vintage movies.
10. old-fashioned or obsolete: vintage jokes.
11. being the best of its kind: They praised the play as vintage O'Neill.
It can also merely mean anything that is obsolete.
The best use of the term would probably be to say 80's Vintage or Early 90's Vintage, that way you are referring to what vintage it is, rather than just calling it "Vintage"
