I think I have found the culprit for the recent wiki server problems: A plugin (datatemplate) was misbehaving, causing memory usage creep and high server load, which resulted in sluggish response times, error messages like "This page is temporarily unavailable" and missing datatables.
I have been monitoring server load for quite a while now and it seems we are back to normal conditions.
Should you experience any further issues like this, please send me a direct message or at least an @-mention so I get alerted.
Sorry for any inconveniences!