Немного поправки, только ради стиля,
My first thought was, "<em>I didn't realise Otto Dix wrote songs...</em>" Then I understood )
We decided/ solved our problems,
Silver tears flow into the veins,
You can't run down (away)/ There is nowhere to run (to),
But all is well, you just have to be silent.
...
You must smile for the sake of survival
You must smile (for the sake of seeming)/ to seem alive.
The harness tightly compresses the veins,
Silver shadows don't find you.
...
We walk / march together,
With song* to in the parade.
*С песней мы на парад. This is quite hard. '<em>With song</em>' looks very simple, but is acceptible in English in a way that is complicated to explain. Normally 'song' requires an article. On the other hand, there is a rare poetical/narrative form that drops articles and pronouns (which I can't explain), such as,
"And he strode out, cane in hand, song in heart..."
Alternatively, you could use:
'...march together,<em> in</em> song in the parade.'
To be together<em> in</em> song/in prayer/in doubt = to be<em> unified by</em> ...verb.
Really good translation