[RPG] Can Warlock’s Eyes of the Rune Keeper decipher written code

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I have a Warlock in the party, and the party came across a message on a fallen enemy. It was written in draconic, and in code.

The Eyes of the Rune Keeper allows the Warlock to read the draconic, But does Eyes of the Rune Keeper allow the Warlock to decipher the code?

Maybe as a side question, if a note is written with a subtle subtext, much like in the way that Thieves Cant is spoken, does that also count for Eyes of the Rune Keeper?

Best Answer

No, the warlock can't understand specific codes or Thieves' Cant

The Eyes of the Rune Keeper states that (emphasis mine):

You can read all writing.

This by itself leaves some room for interpretation. Fortunately, we have more information. The Sage Advice Compendium has a question on this feature:

Does the Eyes of the Rune Keeper invocation work on magical runes?

Eyes of the Rune Keeper lets you read any form of writing, including the linguistic meaning of a rune, if any.

Jeremy Crawford also answered this specific question in this tweet (note that Jeremy Crawfords tweets are no longer official):

Eyes of the Rune Keeper lets you read all writing. That doesn't mean you understand a secret code being delivered by that writing. For example, you might read, "Sunset Dog Potato," and have no idea that's code for something. #DnD

Taken together, this to me suggests that the warlock understands the literal meaning of what is written. Any subtle subtext or special symbols that are not related to a language would not be automatically understood.