Continuation from here.

I tried to solve this with several ways.

1) I imported on l10n server po file for some module with plural forms in header - nothing.

2) I imported on l10n server po file for Drupal core with plural forms in header manually inserted - nothing.

3) I imported po file for some module with plural forms in header on my installation of Drupal, then exported po file from that installation and then imported on l10n server - nothing.
(note: after exporting po file from my installation, code for plural forms changed in header
before: "Plural-Forms: nplurals=3; plural=n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2;\n"
after "Plural-Forms: nplurals=3; plural=((((n%10)==1)&&((n%100)!=11))?(0):(((((n%10)>=2)&&((n%10)<=4))&&(((n%100)<10)||((n%100)>=20)))?(1):2));\n"

4) I imported po file exported from my installation with those plural forms in header (see number 3) to other installation, then exported po file from that installation and imported on l10n server - nothing

So I don't know how to solve this. Same as pvasili described here, on l10n server i can't edit those strings with @count in it, and those exported files from l10n server can't open in offline editor, they don't have plural forms in header, but they have @count in strings. If you could please tell me how you solved this problem, or I need to go to drupal.org and ask Gabor.

BTW, when I import those big po files on l10n server, I receive this page, but strings are imported.