Hey,

Iirc, one of the ways to get contracting scroll is, if you get to the last milestone in Konoha Great Tree.
I'am not 100% sure, but i think one of the milestones in Wheel of Fortune gave also a contracting scroll.
And maybe Treasure of The Sage was also a contracting scroll.

Your answer on the White Tiger Contracting Scroll, I myself have never seen it in any event, so I don't know either.

Please correct me if I'am wrong