That doesn’t capture the “unusually” in “unusually regular”

Ungewöhnlichregelmäßig or Hyperregelmäßig works for me, but then there is Regelmäßigkeitsmonsterhaft.

Still, I think we can push the limits to Bürokratieapokalyptischhyperregelmäßigkeitsgötterungeheuerhaft and feel pretty comfortable with it.

While grammatically feasible, none of these sound natural