HANA 1.0 SPS 12 that is?
Toad for SAP currently supports SPS 09 only, constrained by our parser component. However, the good news is that today we started work on upgrading to version 2.0 SPS 04. Anonymous blocks, such as the one you came up with, will be addressed as early as possible. Can't provide precise schedule, but one month from now will already show a substantially different picture.