I disagree. The first thing I did after I read M’s letter is google “orders of classical columns” because it was mentioned twice and he even said to “take” the order. So I got the column types right away. It was figuring out the cypher that took me much longer.

Hmm, I'm torn on this one. I was able to solve it after identifying it as a columnar transposition cipher based on the text and the imagery, even identifying the size of the corresponding grids based on the number of columns in the image. But after reading about transposition to decrypt this one, I still couldn't manually solve it as the key for doing so was not evident and no transcription of characters into their corresponding grids appeared to yield anything useful. After entering the text into an online deciphering tool I was able to resolve the three clues and arrive at the solution.

Seeing that the actual solution requires you to identify each column's architectural classification (their shorthand nomenclature at that) and use that corresponding terminology as each cipher's key is a huge stretch in logic, especially if you began this puzzle having no idea that different column styles have different names and therefore would be unlikely to think to search for that. I'm left wondering why this puzzle would be deemed "yellow" especially compared to the considerably easier "red" puzzles that immediately precede and follow it (neither of which require any outside knowledge to solve).