Tbf, "learned a language" is a hard thing to pin down in any case.
I've been building enterprise software with python for almost a decade now. I still occasionally find stuff in the stdlibs that I didn't know about, or even sometimes some subtle feature of the language that I never had reason to explore until now.
If someone asks me if I "learned" python, id say hell yeah - but there's always still plenty to learn
That being said, no reasonable definition of learned includes what you could do in 2 days, even as an experienced dev lol
It' basically the Dunning-Krugger curve - you're well enough into the last part of it so you are well aware of how much there is to learn about it and how you will never know all of it, thus you don't have and never will have the same kind of cocksure belief that "I know this shit" as somebody who knows just a bit but not yet enough to understand how much there is to know.
Something like 20 years ago, I learned PHP in 2 days... meaning, I could write better PHP than anyone else on the team.
(not to diss on the team, one was a Java guy who left shortly afterwards, the others were a couple interns, while I had the power of something like 10 years of coding experience... and a PHP cheatsheet-booklet)
That sounds less like you learned the language to a high standard, and more that you were already a good programmer in general terms and everyone else on your team barely knew what they were doing.
Ultimately if you can write good code in one language, you can probably also do it in another (especially with access to cheat sheets), but I still wouldn't call using a cheat sheet having "learned" a language.
Of course it's all relative and subjective - which is the whole point , one person may consider just being able to write syntactically correct statements as having "learned" a language. Where others might expect a deep knowledge of the language features, standard libraries, and best design practices (this is the side that I personally lean, which I maintain can't be done in 2 days)
To be fair, i did cover the Fortran 95 spec in a weekend, but i was motivated to tutor aerospace engineerings as there were far more females there than in Electrical Engineering and Computer Science.
The point is that learning a spec is not learning how to program in the language, just as learning how a violin works is not learning to play the violin. And writing your first few programs is like learning to play Twinkle Twinkle Little Star and The Happy Farmer on the violin. You've kind of learned the violin, but you're not getting into any professional orchestras.