m7.5- transposed to sus#4 b3 ??

[Sandro Santilli]

I transcribed an A major song with this chords snippet:

  ees:m7.5- | aes:7 | aes:m7.5- | des:7 |

When transposing it to Eb major it is rendered as:

  Bbbø | Ebb7 | Ebb7sus#4 b3 | Abb7

I don't understand why the third chord (m7.5-)
gets rendered as a "7sus#4 b3" chord, very hard
to read ...

Ideally I'd also like to avoid the double flats,
but what strikes me is the "sus#4 b3" part, is it
a bug ? I'm using GNU LilyPond 2.18.2 and the
.ly file has a \version "2.18.2" header.

--strk;