I would suggest restoring those libraries back to their original and try and force your application to use the Linux Libraries instead. Have you looked at the command 'brandelf'? This allows you to force an application to use the Linux libraries instead.
# brandelf -t Linux <Unreal Torunament server binary>
Also there is a native unreal tournament server for FreeBSD which maybe worth checking out, you can install that with the following command:
# pkg_add -r utserver
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