First of all, thanks everyone for your messages, and most of all for your understanding. Moving all the posts, members etc. gathered in 10 years is surely quite a heavy and long process, however we needed the change as the old platform is discontinued/doesn't receive any updates from its creators and, besides being slow, it was very prone to hacking.
I'm not sure what happened with some of the posts, as in the conversion bar it showed (and it still shows) that all the posts have been transferred.
As for the search, the new platform still needs to reindex the search table, so hopefully that will fix the search errors.
As for the complete lists of downloads, that was a mod especially made for VBulletin, so they surely won't work for now, but I'll look for a sort of replacement.