Martin, your suspicion is correct, as verified by selecting and copying the string and pasting into code between quotes.  I strongly suspect that tk just sends the string as is to the OS graphics system insert text function, that the latter decides what to display.  I ran
  for i in range(1,33): print(f'<{chr(i)}>')
on Windows console, Windows IDLE, and Mac IDLE (omitting '1' crashes on Mac) and there are multiple inconsistencies.  I believe tcl/tk only documents \t and \n because those are the only two control chars whose behavior is consistent across graphics systems.  Thanks for digging up the previous issue.  I would close as a duplicate if I did not see a need for doc revision.