Hey there (writing from Germany)
Is it possible to modify a single letter (example: shorten the 3 edges of the letter E via anchor points?) but letting it stay writable and not being a vector letter?
If yes, how do i do that?
No. You cannot edit the paths of a single letter with the path tools without converting them to outlines before.
Ok, thank you!
So then it is not possible to convert it back to an fulltext-letter?
Furthermore, it would be an infringement to the font EULA… (in most of the cases)
Not while retaining its unique attributes, no.
You could always "scan" a PDF using Adobe Acrobat's document processing features for type attributes and import it into InDesign as "text" again, but it would lose the design attributes you applied to the former character. At best, you'll be caught in a ground loop between the original text character and your stylized outline.
Du kannst sogar ausschließlich mit InDesign und dem Skript IndyFont eine neue Schrift mit der Modifikation des Zeichens "E" erstellen. Kostenlos, wenn der OpenType-Font nur ein einziges Zeichen enthalten soll:
( ACP )