Sebastian,
So the issue is that in mm. 3-4, the alto lyrics are on a second line? I think this is intentional...each Lyrics context is given a dedicated line on a system. To do what you would want, you would need to combine the Lyrics and set the associated voice (which, given the non-overlapping nature of the two lines, I'm not sure works quite right, in my experience...you may need to add a hidden note in the alto at the end of m. 2 to allow the lyrics to move over seamlessly), or break the system after m. 2.
One of the scheme gurus might be able to come up with something that looks at a a column of lyrics and re-outputs them to accomplish what you want, but I'm at a loss otherwise.
Cheers,
Carl