How to fix mbrola: Warning: v-d unknown, replaced with _-_ (happens with mb-de2, but not mb-de4)

[GithubAnon0000]

My dictsource/de_list contains the following rules:

darkness	_^_EN
of	_^_EN

Running the command espeak-ng -X -vmb-de2 "of darkness." -s20 returns the warning mbrola: Warning: v-d unknown, replaced with _-_.

Full output

Found: 'of' [_^_]   $onlys
Found: 'of' [02v]  $u $only
Found: 'darkness' [_^_]   $onlys
Translate 'darkness'
  1	d        [d]

 36	ar       [A@]
  1	a        [a]

  1	k        [k]

  1	n        [n]
104	&) ness  [n@s]

Translate 'dark'
  1	d        [d]

 36	ar       [A@]
  1	a        [a]

  1	k        [k]

(en)0v d'A@kn@s(de)
mbrola: Warning: v-d unknown, replaced with _-_

Running espeak-ng -X -vmb-de4 "of darkness." -s20 works fine though. There is no warning and the audio is not chopped off.

Full output

Found: 'of' [_^_]   $onlys
Found: 'of' [02v]  $u $only
Found: 'darkness' [_^_]   $onlys
Translate 'darkness'
  1	d        [d]

 36	ar       [A@]
  1	a        [a]

  1	k        [k]

  1	n        [n]
104	&) ness  [n@s]

Translate 'dark'
  1	d        [d]

 36	ar       [A@]
  1	a        [a]

  1	k        [k]

(en)0v d'A@kn@s(de)

I know that mb-de2 uses phsource/mbrola/de2. If I remove all lines in this file below the "// phonemes for English words" comment, any english word is pronounces wrong (silence instead of voice, mbrola prints lots of warnings that look just like the one above). That's why I thought the change is easy. I thought I am just missing a phoneme in that file.

Copying the contents of phsource/mbrola/de4, phsource/mbrola/de6, phsource/mbrola/de8 (one by one as a test) into phsource/mbrola/de2, overwriting phsource/mbrola/de2 in the process, and compiling phsource/mbrola/de2 doesn't fix the problem though. Since mb-de4 works though it has to get the phoneme info from somewhere.

I also copied the entire phsource/mbrola/en1 file into the original phsource/mbrola/de2 file, concatenating both files, just to make sure I'm not missing anything obvious. The same problems persists though.

How can I make it work with mb-de2 as well? Thanks for every pointer!

Edit: In my similar question #2003 the phonemes in de_list where wrong. Is something wrong with the english rules in this case, too?