What's the evidence that the colors were added later?

[oshfdk]

Maybe the omission of those outlines by the original Artist was intentional, maybe not.  But anyway the Painter assumed that they were mistakes, and "fixed" them with his yellow paint.  I consider these instances evidence that the Painter did not have a quill and/or brown ink suitable to draw the missing outlines.  And, therefore, that he was not the original Artist, and could not get him to fix his mistake.

What if there were still visible star outlines made by the original author when the painter was doing the paint job, but since then the outlines faded into oblivion? I'd definitely invoke MRT here if I was pro-MRT.