Can Accelerator be harmed by space-time abilities (such as teleportation)?
As for teleportation, the Railgun wiki says:


  As of Volume 20, he is currently in Russia, where he has a brief encounter with some Russian mages, and some of Academy city's new streamlined, high-speed power suits. It is also during this encounter where we learn that his ability not only works on magic (although incompletely, as the magic is dissipated instead of redirected) but also on teleportation as well.


Supposedly, Accelerator's reflect shield works in all 11 dimensions, so as long as the teleportation is using one of those (as Kuroko's does), he'll be able to reflect it.