interesting you dont thinks its walnut burl…i know you have good knowledge.
I have never heard of anything else other than “straight grain”
On my cars, I considered it to be walnut burl
I have conducted repairs using the old veneer peeled off and patched in…with mixed results
I have also purchased and replaced some walnut burr with new…every batch is very different, in pattern, grain and also color
I believe the 420G used a very light shade of veneer, and its very difficult to get anything light enough to match.
The short piece you show, I would repair with my method if you have enough old matching veneer.
Think I might have already pictured some of my practice pieces in the past…they were firewood, some now better than what is in there