[Unanswered]  Are homemade stickers legal in non-Burst formats?

It recently came to my attention that only the Burst and Burst Classic rulebooks specifically says that homemade stickers aren't allowed (under the "Homemade/Unofficial stickers" section). Every other handbook only says to "respect the legal sticker positioning as outlined by the instructions", which itself doesn't describe the stickers at all.

With this being said, are homemade stickers legal for play in non-Burst formats, or are the other rulebooks in need of an update to add the rules that already exist in Burst regarding homemade stickers?