Learning from encounters is compartmentalised into seeing the same or similar mechanics again. Seeing one boss with untelegraphed attacks doesn't teach you anything for a later boss that is completely different in its movements and effects.

The logical learning curve for me would be that the Coincounter - being the first cyclops you encounter - has telegraphs, and subsequent monsters of the same type/animations can then perform the same attacks without telegraphs because now you have learned what to expect and what to look for.