I don't see how what you said disagrees with what I said aside from a minor semantic quibble. You can't parse any other language with certainty without knowing all the keywords either. For example, in Ruby, you might see the identifier "continue" by itself. Is this a method call, variable access or keyword? What about "private"? No way to know if you don't know all the keywords. This is precisely cognate with nene's objection that you can't tell whether "new" is a keyword in Zinc if you don't know the language's keywords.

You can form a rough guess of what the various tokens are in a snippet of Ruby code without knowing all the keywords, and you can do the same with Zinc code. Any additional difficulty is most likely because you're less familiar with Zinc, not because it has the nearly universal property of needing to know the full grammar to correctly parse arbitrary programs.

And I agree, playing around with a language is a great way to learn. But if you play around without reading about the things you're doing first, you should expect not to always know what you're doing. That's a huge part of the learning process.