Are there any cases of Illegal Building in an official lego build?
As mentioned by you already, you cannot insert plates between studs (this used to be a valid technique 20+ years ago, but is no longer considered &quot;legal&quot; by LEGO)

This technique is used in 21309 Saturn V, to mount the flag piece as part of the moon diorama.
Given this set was released in 2017, I’d say its definitely a modern usage.