yeesh, "online English." L337 h4xors with uber skillz?
"achieving unlock" is grammatically incorrect (im a native English speaker), if its idiomatic then of course that's different, but I wouldn't put that down as being "fluent," id put it down to be exposed to those specific idioms. It's not just about using the verb as a noun; where is the indefinite article?
If the gp was making a "I can has cheeseburgers?" style joke, then it went over my head, but it clearly is not grammatically correct English just because its used online.
It's incorrect English. If its idiomatic then its idiomatic. But its not a marker of fluency; its a marker of being exposed to a culture which uses those idioms.
An unlocking would be less idiomatic IMO.