Hi, Peter, good to see you here en anglais.
I can't add anything except to confirm what wupper has said. I'm also not a professional musician, as you know, and the last program I used for music writing was Encore, not Finale or Sibelius. But like wupper, I'm reasonably familiar with musical notation, and I've never known any particular word for the signs you ask about.
'Measure repeat' (or perhaps 'Repeat measure,' with 'repeat' understood as a verb in the imperative) seems the clearest to me too for 27-4. 'Repeat sign' is indeed something else, namely ||: -- but as long as you use the word 'measure,' that shouldn't be a problem. Or you could use 'symbol' instead of 'sign.'
27-1 is more familiar to me than 27-3, but I don't know anything to call either of them except a hash mark or a slash through the stem of the note. If there's a more formal name for them, I'm afraid I don't know it.
Unless any BE speakers comment (they may say 'bar' instead of 'measure,' for one thing), that may be the best we can do, sorry.
(Where was that thread about lexical gaps for things? Maybe this is one in English.)
The Abweichende Formen at the very end are certainly, er, abweichend. I had never heard of Viertel- and Sechsteltonmusik and am glad not to have to try to play it. (-: