How did Scotty know how to use a 20th century keyboard and computer?

Yeah, I questioned that back on IMDB and got absolutely hammered for it - and no, I didn't call it a "plot hole" or even call it an error. Just an observation.

Anyone who knows anything about computers knows you can't draw advanced 3D graphics with just a keyboard in a couple of dozen keystrokes on any computer, much less an 80s Macintosh. In fact, even people who didn't know anything about computers knew that.

The way I would have written that scene would be to have Sulu hand Scotty a self contained circuit card that he fabricated that contained both the transparent aluminum formula and 3D graphics on it before he went to visit the plexiglass company. Sulu would say: "here Scotty, just load this into slot where the floppy would go". Scotty could have said with surprise: "a floppy did you say??"

Kirk had an antique Commodore PET in his San Francisco apartment in The Wrath of Khan.

I'm sure Scotty studies up on ancient tech

This crew has time traveled on a few occasions, maybe they studied up on old tech so that they would be prepared?

I doubt the keyboard will ever change. But yeah, knowing whatever software that was and being able to crank out a molecular diagram on it like he was riding a bike is kind of corny.