Hallo Jan Thomas,
you are right, that SAP does no longer offer the unsupported Eclipse Theme Editor for download on SCN. We therefor updated the download page content with the following information
Eclipse Theme Editor version 2 plugin replaced by UI theme designer
This page formerly provided the Eclipse theme editor plugin for defining and maintaining custom themes for SAP applications. Like described in SAP Note 1613933 the Eclipse theme editor got provided via SDN as download under the terms of an evaluation license that did not imply support from SAP, and limited usage to non-productive scenarios.
Beginning with UI add-on 1.0 SP4 for SAP NetWeaver and with SAP NetWeaver 7.40 SP3 SAP offers the UI theme designer as single solution for theming and branding SAP’s key user interfaces across multiple SAP UI clients (SAP NetWeaver Portal or SAP NetWeaver Business Client), technologies (SAPUI5, Web Dynpro and Floorplan Manager) and applications (SAP Business Suite, landing pages in HCM Renewal, SAP Fiori).
Comments and questions: Please use the User Interface Technology forum to provide your feedback or to post queries.
More details: see http://help.sap.com/nw-uiaddon (UI theme designer devloper guide under section "What’s New – Release Notes - English (PDF) - Chapter 3") and SAP note 1852401
Regards, Bertram Ganz, SAP AG