There was something about enchantments losing their enchants, as well as the /mbox plugin breaking sometime back then. As I recall, mods did NOT refund spawners for the plugin, because people began lying about what their spawners were supposed to be. There was no way for the mods to confirm that the spawners were what people claimed, and so they did not refund any spawners (to my knowledge). What happened to your spawners could be because of a plugin fail, or it could be for some other reason. Good luck getting your spawners back <object class="emojione" data="
https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/2639.svg?0" type="image/svg+xml" standby=":(">:(</object> Spider and skeleton spawners aren't that expensive anymore. I've seen some shops selling for ~4k-5k per egg. Its a pretty big loss, but it isn't that bad.
P.S. The same thing happened to me when the /mbox plugin broke. I lost about 10 skeleton spawners, ~4-6 spider spawners, and ~2-3 zombie spawners. Now I have almost a stack of pig spawners that I have no idea what to do... xD (I originally had some pig spawners before /mbox broke) I feel your pain buddy. I hope this gets resolved quickly and you get refunded!