I've seen lately that videos have been getting taken down on YouTube or DailyMotion due to copyright. But why not upload the nightcore versions of the songs? They don't get taken down so it'll be so much easier on your part. Yes, the voices are more higher and the song is a little faster but it's not too bad. It's better than having to reupload videos on this wiki all the time.
There's this channel I'm subscribed to which has the Symphogear songs but the user has edited the songs to make the voices just a little higher but the speed is the same. S/He doesn't have all the Symphogear songs though. Here's the link to the channel: https://www.youtube.com/channel/UCSpqTtu0UK3QfWVCcHe13BQ