I can take full credit for this one, I don't think I ever saw it mentioned anywhere in 3 months.

Secret bosses getting Shadow crystals being referred to as "a tear shed for them" is alluded to as far back as the start of chapter 2

TOBY
not only is this directly confirming the "ramb was supposed to be the secret boss", but ALSO the Jigsawry is making a FRIENDly face when talking about shedding a tear for a boss