What a tragedy, branzino. I feel for you. So frustrating.
It looks like the letter was filed back: the depth of the letter (from the face of the slug to the point where the letter touches the platen) is shallower in the lowercase e than the capital E, and the corner is filed off even more. The only way to rescue it would be to file it all back so that it is the same height from the face of the slug (thus the entire letter contacts the platen), but that will also make it bolder since the letter strokes get thicker as they go back to the slug body.
For finding a replacement: Many European typewriter manufacturers used type slugs from companies that specialized in type slugs - e.g. RaRo aka Ransmeyer & Rondrian type slugs are on many different manufacturer machines. I wonder if you find a donor machine from another manufacturer that uses the same slugs.
The 12 on these slugs doesn't match any RaRo styles that I could find on the catalogs on munk.org, but perhaps it matches another manufacturer?