you can pm one of the players in that game and ask them to send their local copy to you (using some filehoster/dropbox/...).
I dont know of any other way to retrieve it. If the file is not stored on the server, well you cant get it from there then :/
Some time ago there was a huge poll for suggestions about what to improve on FAF, fixing replays (i.e. corrupted/desynced/not-uploaded replays) was one of them (acually from me). It got quite high up in the list, but it wasnt considered, because there is too much work related to it (according to the developer conference about this poll).
Feedback-poll:
https://feedback.userreport.com/7a3715d ... as/populardev conference (not sure which one):
https://www.youtube.com/results?search_ ... conference