So Simon Letch's Sunbow Marvel Archive, has published a 333 page set of Flint Dille owned documents.
The Sunbow Marvel Archive: Transformers: Flint Dille's Character Binder

Contained within is Bruticus's unpublished Tech Spec 38 years late.
Fan were using a Japanese write-up as a substitute all these years.

 

Does the Japanese tech spec bio took reference from these notes? They generally mention similar feats like smashing bridges.

 

Presumably the Hasbro binders would have been shared with Takara and translated to Japanese.